Advances in River Sediment Research – Fukuoka et al. (eds)© 2013 Taylor & Francis Group, London, ISBN 978-1-138-00062-9

Need for analyzing spatiotemporal patterns of river-corridor habitat
structure in sediment management
M. Hyodo, Y. Takemon & T. Sumi
Disaster Prevention Research Institute, Kyoto University, Kyoto, Japan

ABSTRACT: Spatiotemporal patterns of river-corridor habitat are determined by flow and morphological regimes and they should be integrated in the ecological evaluation. Existing habitat evaluation
tools, however, lack this perspective. Even though some recent studies highlighted spatiotemporal patterns, e.g., shifting habitat mosaic steady state concept and habitat age, they do not address processesof changing patterns of each habitat unit, e.g., riffles, side pools, and back waters. We propose a habitat
diversity hypothesis, defined as: spatiotemporal patterns of habitat structure determine biological diversity, which can be characterized by a function of intensity and frequency of disturbances and age of eachhabitat unit from its disturbances. In order to prove our hypothesis, we started a case study in a middle
reach of the Tenryu River Japan. Data collected by several interval recording cameras enable to transform
into 2D and 3D data and to quantify spatiotemporal patterns.

1
1.1

INTRODUCTION
Background

Various habitat evaluation tools have been adopted
in decision-making processes in flood and water
resources management. For example, Habitat
Evaluation Procedures (HEP) quantifies the overall suitability through time by integrating the areal
extent-suitability product function over time via
habitat suitability indices and thus can quantitatively compare two or more alternative management practices of an area with regards to thosepractices affecting species (US FWS 1981). PhysicalHabitat Simulation Model (PHABSIM) predicts
physical microhabitat changes associated with flow
alternations such as microhabitat, physical habitatand life stage changes (US FWS 1986). AustralianRiver Assessment System (AUSRIVAS) makes anassessment of physical stream condition using theprotocol, which requires a large number of reference sites sampled (Parsons, Thoms, & Norris2001). River Invertebrate Prediction And Classification System (RIVPACS) assesses the biologicalquality of rivers offering site-specific predictionsof the macroinvertebrate fauna to be expected in
the absence of major environmental stress (Wright,
Sutcliffe, & Furse 2000). Index of Biotic Integrity(IBI) quantifies changes in ecosystem health as aresult of habitat degradation or flow alteration,in addition to chronically poor chemical water
quality (Karr 1981 & Karr & Dudley 1981). Mostof these tools can evaluate current habitat suitability based on physical characteristics or habitat

spatial distributions. These tools are useful whencomparing several options to determine mostappropriate one (s) that can avoid negative consequences to the ecology of rivers and thus often
used in decision making processes, e.g., exploring
mitigation measures.
Recently, the shifting habitat mosaic steady state
concept appeared and it was known as: “Locationof aquatic habitats in floodplains changed considerably (turnover), whereas habitat configurationand composition remained relatively stable. These
results support the applicability of the shiftingmosaic steady-state model to riverine floodplainsenvironments (Arscott et al. 2002)”. Further, it isshown that there is a need to address habitat diversity in relation to biological diversity (i.e., species
abundance and richness) and there is implicationthat habitat diversity maximizes biological diversity (Takemon 1997). Further, importance of temporal patterns, i.e., habitat age, was also highlighted(Arscott et al. 2002).
From a different perspective, other studies on
analyzing material cycle efficiency showed that
habitat structure is considered important forparticulate organic material (Ock et al. 2010 and
Ock & Takemon 2011), and habitat conditions
change in spatial and temporal distributions andthus implicated that temporal patterns are also the
key to addressing habitat structure (Takemon et al.
2008). These results explain the importance ofconsidering dynamic state of changing habitat.
Nevertheless, existing habitat evaluation tools
lack this perspective: changing habitat in its

1557

Table 1. A review of river restoration projects through channel widening & creating secondary channels for ecologicalrestoration. Particular attention was placed on substantial factors determining the fluvial processes: the river shape,morphological regime, and flow regime. Some projects from USA, Europe, and Japan were selected for the review.
River

Year

Country

Restoration option

Target habitat restored

TP*1

SA*2

FR*3

Drau River

1999

Austria

No

No

2006
1996
2003

Japan
Netherlands
Switzerland

No
No
No

No
No
No

No
No
No

Tama River
Mana River

1996
2003

Japan
Japan

Channel widening
Secondary channel creation

No
No

Yes
Yes

No
Yes

Trinity River

1991

USA

Channel widening

River islands andgravel banks
Gravel banks
Secondary channels
Shorelines and gravel
banks
Gravel banks
Pools, gravel banks, &vegetation
Riffles & pools andpoint bars

No

Chikuma River
Waar River
Thur River

Secondary channel
rehabilitation
Channel widening
Secondary channel creation
Channel widening

No

Yes

Yes

*1TP: Temporal patterns of habitat structure were considered.
*2SA: Sediment augmentation was implemented.
*3FR: Flow regimes were modified, e.g., through reservoir operation and managed flows.

habitat age: intensity and turnover rate of spatiotemporal patterns that determine biodiversity.
1.2

monitor dynamic changing habitat and quantify
its spatiotemporal patterns including erosion anddeposition processes.

Objectives

Spatiotemporal patterns are determined by flow
regimes and morphological regimes, e.g., deposition and erosion, and sediment transport fromupstream. Therefore, they should be integrated
in the ecological evaluation. When spatiotemporal patterns are addressed, flow and morphological regimes should be considered as explanatory
variables. In this context, firstly we conducted areview on ecological restoration of river corridor habitat, particularly through channel widening and creating secondary channels. We selected
well-known restoration projects, which have been
implemented in USA, Europe, and Japan (seeTable 1). Our particular attention was placed onwhether or how flow and morphological regimes
are considered to restore fundamental ecologicaland fluvial processes through particular management options, i.e., reservoir operation and managed flows, and sediment augmentation. Secondly,
based on the review, we identified key challenges
and propose a habitat diversity hypothesis in orderto evaluate spatiotemporal patterns, which is a different approach from the intermediate disturbance
hypothesis. Thirdly, in order to prove our hypothesis, we introduce our case study, which started inJuly 2012 in a middle reach of the Tenyu Riverin Japan, where several interval recording cameras(hourly) were placed at 60 m high from the riverbed in the center of the river corridor. Throughseveral camera-recording, the photo data can betransformed into 2D and 3D data, enabling to

2 ECOLOGICAL RESTORATION:
CHANNEL WIDENING AND CREATION
OF SECONDARY CHANNELS
2.1

Drau River in Austria

The upper Drau in Carinthia had been a highly
braided river with many side arms and gravel banks.
In the 20th, the riverbed was canalized, bends werestraightened out, branches were cut off from themain stream, dams were built, and farming in thefloodplain area was intensified. These interventions have brought an enormous loss and degradation of the natural freshwater habitats including
alluvial forests and a decline of species populations
including the Danube salmon (Hucho hucho) andthe crayfish (Austropotamobius pallipes). Major
problems occurred include the deterioration ofnatural flood retention capacity leading to greatrisk of flooding. Deepening of the riverbed, e.g.,
2 cm per year, caused a fall in groundwater tables(Mohl 2012).
The restoration measures were implemented infrom 1999 to 2003 for a river length of 7.6 km aspart of the LIFE Nature project “Auenverbund
Obere Drau”, which became culminated in oneof the largest river restoration projects in Europe(Formann et al. 2007). The restoration project
aimed to prevent from further riverbed degradation, to re-connect the river with its floodplainarea and to initiate the development of typical1558

Figure 1. Drau river before and after rehabilitation
2003. (Mohl 2012).

habitats of the riverine landscape (see Fig. 1).
Bank stabilization structures were removed and theriverbed was widened. Lateral erosion increased
the sediment input and initialized the developmentof gravel/sand bars and islands. One of the former
side arms was reconnected to the river for annual
flooding. The second side arm was widened to awidth of 30 m creating diverse instream structures
and thus increasing habitat diversity of the aquatic
environment (Mohl 2012). The monitoring of themeasures has shown positive results including:better flood prevention; reduced flow velocity;
decrease in riverbed deepening even rose; created
50 to 70 ha more natural river habitats as riverislands, gravel banks, steep banks for engendered
species such as Danube Salmon, Common Sandpiper and Kingfisher created; and fish population
doubled such as the grayling (Mohl 2012).
2.2

Figure 2. Channel widening of the Chimuma River,
illustrating before, just after, and some period after the
restoration. (Ishikawa et al. 2010, English words added)
Some plants are vegetated in Awasa district (a) the left
column, but nonnative plants are not identified even after
4 years after the restoration. Even though a period one
year is not long enough after the restoration in Nezumi
district (b) a right column, native species are dominant
instead of being invaded by nonnative plants.

Chikuma River in JapanThe Chikuma River, which is called in the Nagano
prefecture, is part of and located a middle reachof the Shinano River that is the longest river inJapan. The Chikuma River has been covered bygravel riverbed and plenty of native plants andanimals. However, as same situations as the TamaRiver (see Section 2.5 for details), intensive gravel
miming caused degradation of average riverbed;
inundation frequency of floodplains got lost due
to development for human use; and embankments and straightening of rivers fixed rivermorphology, resulting in loss of habitat diversity
and native plants. These interventions as a consequence caused increased local sedimentation andnonnative plants, e.g., Ambrosia trifida and Sicyos
angulatus, and woods, e.g., Robinia pseudocacia(Chikuma River Ecological Research Group et al.
2010 & Ishikawa et al. 2010).
The Cikumagawa River Works Office of MLIT
and Chikuma River Ecological Research Group
conducted a river restoration project since 2004
through channel widening with a view to restoring native plants as well as impeding invasion andgrowth of nonnative plants, as part of riparian
forest and river management. The two study sites
were selected: the Awasa district conducted in 2006
is located a 81 km point of the Chikuma River,average riverbed slope is 1/510, mean particle size
is 40 mm; on one hand, the Nezumi district conducted as the reference site in 2009 is steeper thanthe Awasa reach located a 98 km point, average riverbed slope is 1/220, mean particle size is 53 mm.
were selected in the Chikuma River (see Fig. 2).
The Awasa district restoration showed thatchannel widening enabled to restore native plants
within a short term. A large flood event occurredin July 2006, 3 months after the channel widening, showed that reinvaded nonnative plants were
flushed away from the study site and gravel riverbed and aquatic native plants were sustained. This
explained the potential to maintain gravel riverbed if widened channel keeps one year frequency
of inundation by a certain flood event (annual
flood discharge). Small flood events occurred in
the Nezumi district also contributed to increasing

1559

native plants in stread of allowing for nonnativeplants to grow. In addition, at both sites, benthic communities temporarily lost due to channel widening, e.g., Chironomidae, Trichoptera,and Ephemeroptera, were recovered within a few
months, implicating further potentials to the outreach of restoration activities.
2.3

Waar River in The Netherlands

Garmerensche floodpains are located in the
Waar River, a lower reach of the Rhine River in
The Netherlands. After a flood event 1995, large
amount of clay and sand were excavated and secondary channels were created as part of flood
management project including dyke improvement(Baptist & Mosselman 2002). This project also
aimed at creating through secondary channels thenature development of flora and fauna as shownin Figures 3 & 4.
Characteristics of the three secondary channels
of west, east, and large ones differ: the west andeast channels have a sill at the entrance openingthat determines the flow frequency; and the larger
channel does not have a sill but permanently flows(Baptist & Mosselman 2002).

The geomorphological processes were monitored by the Institute for Inland Water Management and Wastewater Treatment (RIZA) andrevealed that the east and west channel flow more
often than the design frequency. Total sedimentation in the east and west channels since 1996 to1999 reached to about 5 cm in three years at theentire channels (Baptist & Mosselman 2002). At
the same time, secondary channels also caused erosion, where it is not allowed, for example near winter dikes, infrastructure or heavily polluted areas.
It may require defense of the banks with stones.
Since limits are usually put on the permissible rateof erosion and sedimentation in secondary channels, maintenance measures such as dredging or
defending banks can be necessary. It is practically impossible to design stable secondary channels while taking all preconditions into account.
Therefore, maintenance activities and monitoring
are then needed (RIZA 2001).
2.4

Thur River in Switzerland

The Thur River is located in north east of
Switzerland, flowing along the Swiss north east
Limestone Alps. Switzerland’s watercourses havebeen severely degraded by flood control measuresand other engineering operations. This is also trueof the Rhone and Thur Rivers, which have largely
lost their ecological diversity and characteristic
landscape features (Peter 2006). For this reason,increasing efforts have been made to rehabilitate
watercourses by the Rhone-Thur research project.
The aim of this project is to remedy deficiencies in theexisting flood control system and, at the same time,to enhance the Rhone ecologically. Figure 5 shows
the Thur River at Altikon-Niederneunforn before

Figure 3. Locations of secondary channels in theGamerensche floodplains in the Waar River (Baptist &Mosselman 2002).

Figure 4. Sedimentation and bank erosion occurred at
the secondary channels in the Gamerensche floodplainsin the Waar River (RIZA 2001, photos taken by Jans L.).

Figure 5. Thur River at Altikon-Niederneunforn before
and after the channel widening (Peter 2006 including
photos).

1560

and after the channel widening (Peter 2006). This
channel widening involved a stretch of 1.5 km of
the river, which was the most extensive local widening project in Switzerland. Particularly increasein shoreline length resulting from the developmentof gravel banks can be highlighted. The new habitat types that emerged were rapidly colonized byplants and wildlife (REFORM 2012).
In this Rhone-Thur research projects, ecologicalsuccess by channel widening of five river stretches
were assessed in detail before and after widening:
the Emme at Aefligen, the Thur at Gütighausen,
the Rhone at Chippis, and the Moesa at Grono andLostallo. The indicators chosen for this purpose
were parameters that describe landscape structure,e.g., habitat type, diversity, size and shape, distance
between two areas of a given habitat type, and habitat boundary length (Rhode 2004 & 2006). For theassessment, values were determined for the indicators and were transferred to a unitless index, witha scale from 0 to 1. The value “0” represents theinitial channelized state, and “1” the desired nearnatural target state. Through the assessment, thechannel widening achieved a relatively high degreeof naturalness (Rhode 2004 & 2006).
The assessment indicated that the remaining deficiencies in comparison with near-naturalreference sites are due to the lower habitat diversity and patchy structure arising from the limited
spatial extent of the widening. The Thur stretch
was found to be less successful as compared toother sites. This is partly due to the fact that thegravel bars at this site are less substantial and thus
more frequently flooded (Rhode 2004 & 2006).
It is important to identify stretches of rivers thatare particularly suitable for channel widening on
account of favorable ecological conditions andthus appear to offer good prospects of success(Rhode 2006).
2.5

Okouchi dam in 1957; and fixing of river shapesby embankments, straightening, and creation ofless frequently inundated area for human use suchas parks, camping area, and baseball and football
fields. Such human interventions caused: reduced
sediment supply from upstream (particularlycoarse sediment but not fine one), leading to degradation of average riverbed elevation; reduced
inundation and disturbance on floodplains,resulting in intensive fine sediment deposition on
relatively higher floodplains where are less frequently inundated; increased nonnative woods(e.g., Robinia pseudocacia) thereon replaced withnative plants; and thus loss of habitat and species
diversity of rivers (see Fig. 6).
The gravel-bar restoration project was conducted in the Nagata district of the Tama River,with a view to increasing frequency of floodplain
inundation by channel widening and thereby restoring gravel-bars, native plants, and species dependent on such gravel-bars (Shimatani 2003 & Unno
et al. 2006). The restoration projects have started
since 1996 by the Keihin River Works Officeof MLIT and Tama River Ecological ResearchGroup. Characteristics of the project are composedof two parts: (i) channel widening was made at 52
to 53 km points in which different five types ofbed elevation (i.e., different inundation frequency)
were selected and (ii) sediment augmentation was
installed at 3 km upstream of the restored reach ofa 56 km point (see Fig. 7).
The results showed positive consequences.
Gravel-bed restoration through channel widening increased native plants and species, e.g., Asterkantoensis and Charadrius placidus. The widened channel shape became stable and slightly
deposited. Sediment augmentation of 5000 m3 peryear upstream has the potential to stabilize the riverbed elevation (Unno et al. 2006).

Tama River in JapanThe Tma River has been most consisted of gravel
riverbed in Japan and is under management of
Ministry of Land, Infrastructure, Transport andTourism (MLIT), of which: catchment area is1240 km2; river length is 138 km including major
tributaries; average bed slope is 1/218; and riverwidth is approximately 300 m in mean annual
flood discharge (almost bankfull) of 1300 m3/s.
The Tama River has formed gravel bars mostly
braided and has provided habitat for nativeplants and animals requiring gravel riverbed,
e.g., Aster kantoensis, in 1950s (Nakamura et al.
2006). However, intensive human interventions
made in 1960s to 1990s altered fluvial processes
by: e.g., gravel bed mining prohibited in 1965
(most severely affected); construction of the

Figure 6. Aerial photos of Nagata district in 1974 and1995 (Unno et al. 2006). The gravel bed on the right floodplains 1974 was replaced with vegetation and tree covers
1995. Fine sediment was severely deposited on the rightside and frequency of inundation was drastically reduced.

1561

Figure 7. Channel widening and sediment augmentation in 2001 (Unno et al. 2006, English words added).
Sediment augmentation (see the photo of the left bottom)
was carried out 3 km upstream of the study reach at theamount of 1800 m3 in Feb. 2001, 4000 m3 in Feb. 2002,
400 m3 in May 2002, and 4300 m3 in Feb. 2003.

2.6

Mana River in JapanThe Mana River is located in the Fukui prefecture,
flowing to the Kuzuryu River. In the upstreamof the Mana River, several dams are constructed:
from the upper reach, the Kumokawa dam in
1956, Sasogawa dam in 1965, and Managawa damin 1979 at the downstream reach, 14 km from theKuzuryu River. These dams play important roles inflood mitigation and electric supply for the Fukuicity. Since the Mana River does not have relevant
tributaries below the Managawa dam until it meets
the Kuzuryu River, it causes negative impacts
such as fixing of river shape, processing riverbedarmoring, resulting in coarse sediment not allowing for fluvial processes, and intense vegetation
and wooden floodplains (Kumagai 2009).
The Kuzuryu Dam River Office of MLIT has
started a restoration project. Artificial floods via
reservoir operation have been carried out since 2003
and maximum 45 m3/s flood discharge for 2.5 hours
was installed since 2006. This flood discharge wasadopted based on a result of previous studies that
attached algae to sediment can be flushed and thus
effective for restoring morphological regimes of the
Mana River (Sakamoto et al. 2006).
In 2007, rehabilitation of a secondary channeland sediment augmentation were integrated into
artificial floods with a view to restoring gravel riverbed, instead of intensive invasion of woods onto
floodplains, habitat diversity, and habitat preferred
to fish communities (see Fig. 8). A secondary channel created at the middle reach of the Mana River
upstream of the Kimigayo bridge has the channel
width of 20 m, length of 100 m, riverbed slopeof 1/82 as the same slope as the main channel,
and deepened down to a elevation that does notallow for flowing less than mean flow discharge.

Figure 8. Monitoring results of rehabilitated the secondary channel and sediment augmentation (Kumagai2009).

The sediment augmentation of 330 m3, consistedof excavated sediment for the secondary channeland deposited sediment of the Managawa dam,
was placed with the width of 10 m (i.e., one third
width of the main channel), its length of 10 m at
the main channel, and inundated at peak dischargeof artificial floods (Kumagai 2009).
The results showed, for example in 2007, that:a deep pool was created at the entrance of the secondary channel; gravel bars were created at its outlet; and 115 m3 of sediment placed were flushed
downstream. The monitoring results identified
increased vegetation, and increased habitat diversity in the form of a pool and gravel bars, and species diversity in response to benthic communities
between the main and secondary channel. This
restoration project through integration of channel rehabilitation, artificial floods, and sedimentaugmentation implicates its potential to becomea trigger for restoring morphological regimes andcreating habitat diversity suitable for fish and benthic communities (Kumagai 2009).
2.7 Trinity River in California, USA
The Trinity River begins in the rugged Trinity
Alps in northwestern California. It tumbles
through steep canyons and meanders throughbroad valleys until it joins with the Klamath
River to flow into the Pacific Ocean. In 1958, aplan was executed to increase water supplies in
California’s Central Valley in part by transferring
water from the Trinity River into the Sacramento
River known as Trinity River Division (TRD).
This diverts 90% of the river’s flow exported fromthe river each year. Trinity and Lewiston dams
were also completed in 1964. The impacts of land

1562

use and dams combined to push the river past its
regenerative capacity. After the dams were completed, the extent of habitat alteration and decline
in salmon and steelhead populations became
obvious by 1970.
The plan is to implement recovery of the Trinity River and its fish and wildlife populations.
Restoring the Trinity River requires a combinationof actions that: re-establishes the natural physicalprocesses that creates and maintains high quality
aquatic habitat; and creates spawning and rearing conditions downstream of the dams that bestcompensate for lost habitat upstream, including
adequate water temperatures (McBain & Trush,
Inc. 2000). This strategy does not strive to recreate
pre-dam conditions, but rather to create a dynamic
alluvial channel, exhibiting all the characteristics ofthe pre-dam river but at a smaller scale. Particularattention was placed in the project to, but not limited to: channel rehabilitation, flow management,
and sediment augmentation. Channel rehabilitation removed riparian berms that confine the river,and relocated sand contained in the berm outsideof the floodway (Figs. 9 & 10).
Floodplains will be constructed to be periodically inundated by flows 170 m3/s and larger. Then
it is expected to create riffles, pools, and gravel/
cobble point bars, improve channel dynamics, andincrease salmon spawning and rearing habitat.
Observations at rehabilitation sites constructed
between 1991 and 1993 have shown that once
the riparian berm is removed and new bars haveformed, flow and coarse sediment management iscapable of maintaining the desirable channel morphology (McBain & Trush, Inc. 2000).
For flow management, in order to recreate interannual, or “between-year” flow variability, fivewater year types with a minimum volume of water
to be released into the Trinity River were designed
as shown in Figure 11. The quantity and quality

Figure 9. Sheridan Creek Bank rehabilitation site with
newly formed gravel bars. (McBain & Trush, Inc. 2000).

Figure 10. Sketch of channel rehabilitation. (McBain &Trush, Inc. 2000).

Figure 11. Flow schedules of five water year types in intra-annual or “within-year” flow valiability (McBain & Trush,
Inc. 2000). Note: 1 Cubic Foot  0.0283168466 Cubic Meters.

1563

of spawning and rearing habitat for salmon andsteelhead varies with flow levels. The relationshipbetween streamflows and habitat, developed during years of the field study, was used to determine
the preferred flow releases for riverine life stagesof chinook salmon, coho salmon, and steelhead.
Habitat is maximized at 4.2 m3/s for some life
stages and at higher flows for others. Within theexisting channel, 8.5 m3/s provides the best balance
for juvenile rearing and adult spawning habitat(McBain & Trush, Inc. 2000).
Coarse sediment management is to increasecoarse sediment storage in the river (gravel/cobblebars), improve coarse sediment transport, andrestore a balance between coarse sediment supply and coarse sediment transport using highflows and mechanical gravel introduction. If theriver were considered a conveyor belt periodicallytransporting and depositing coarse sediment, theproposed restoration strategy would add coarse
sediment at the upstream end of the conveyor belt
at a rate equal to what the conveyor is moving, suchthat accumulations (at tributary deltas) or deficits(channel incision and armoring) are minimized(McBain & Trush, Inc. 2000).
3
3.1

HABITAT DIVERSITY HYPOTHESISThe analysis of the review

All the seven case studies on ecological restorationin USA, Europe, and Japan have been addressing
restoration of some parts of spatial habitat structure, depending on their project scale and goals
such as: gravel banks (e.g., Drau River, Chikuma
River, Thur River, Tama River, and Mana River)and riffles and pools (e.g., Mana River and Trinity
River). However, approaches to achieving theirgoals are different. While some projects addressed
only modifying river shapes locally (e.g., ThurRiver, Drau River, Waar River, and Chikuma
River), but the other projects addressed operationof flow or morphological regimes in an integrated
manner (e.g., Trinity River, Tama River and Mana
River). Only two case studies of the Trinity Riverand Mana River integrated restoration of bothflow and sediment regimes into their restoration
projects (see Table 1). From a perspective of temporal patterns, little case studies addressed temporalchange of habitat structure, except for some local
deposition and erosion processes. Through thereview, we found that flow and morphologicalregimes, which can be considered as explanatory
variables for spatiotemporal patterns of habitat
structure, have been addressed by only a few casestudies. In the review however, it should be noted
that: case studies are in the ongoing processes ofdetermining desirable spatiotemporal patterns ofriver corridor habitat and how they are evaluated;
and that options for ecological restoration should
be adopted based on appropriate combination offlow and morphological regimes (Kantoush et al.
2011 and Sumi & Kantoush 2012). Importantly,
for some case studies, flood management objectives are at center of their restoration projects (e.g.,Drau River and Chikuma River) based on a concept that restoring some part of fluvial processes
can contribute to, for example, lowering of waterstages during flooding, instead of constraining
flood water in channelized embankments.
Various existing ecological evaluation tools, as
discussed in Section 1.1 address spatial distributionsof habitat structure but do not address spatiotemporal patterns of changing habitat. There is, therefore, a need for analyzing spatiotemporal patternsof habitat structure. However, questions may beraised: how dynamic state of changing habitat
can be evaluated and integrated into restoration
projects; and how goals for successful restoration
can be set.
3.2

Habitat diversity hypothesis

Intermediate disturbance hypothesis is one of keys
to discussing evaluation of species richness, originally developed for marine intertidal communities(Connel 1978). This hypothesis explains that disturbance of intermediate intensity and frequency will
maximize species richness by reducing density of
dominant species and create habitat for more fugitive species in inter-specific competition. However,since some communities of species can exist inintermediate disturbances, another approach toevaluating biological diversity may be needed rather
than a concept of inter-specific competition. Other
studies showed that there is a need to address habitat diversity in relation to biological diversity (i.e.,
species abundance and richness) and there is implication that habitat diversity can maximize species
diversity (Takemon 1997). A study conducted inrivers in New Zealand showed that ratio of surface
sediment in its relation to species richness had similar results with the habitat disturbance hypothesis(Townsend et al. 1997 and Matthaei et al. 1999).
Even though this result does not analyze relations
between habitat diversity and species diversity, it
implicates the possibilities. Therefore, spatial heterogeneity should be addressed.
On one hand, temporal patterns are also highlighted. The shifting habitat mosaic steady state concept, addressing some parts of temporal patterns,
explains that habitat changes in shifting mosaic andassembles of spatial distributions of habitat structure get almost stable and this steady state supports
riverine environment (Arscott et al. 2002). Habitatage is another approach that analyzes continuity

1564

of habitat structure in a reach and understands
that existence of diversity of habitat age in a reachsupports species diversity (Arscott et al. 2002).
An attempt to address temporal patterns in formof habitat age is important, however, this neither
tracks processes of temporarily changing patternsof each habitat unit, e.g., riffles, pools, side pools,
and back waters, nor addresses quality of changing
habitat, i.e., changing patterns of microhabitat ineach habitat unit (macro habitat). The discussions
above highlighted a need for analyzing spatiotemporal patterns of river corridor habitat structure,in which flow and morphological regimes can be
explanatory variables.
We propose the “habitat diversity hypothesis” toanalyze spatiotemporal patterns of habitat structure. We define the habitat diversity hypothesis
as: Spatiotemporal patterns of habitat structure
determine biological diversity (i.e., species abundance and richness), which can be characterized
by a function of intensity and frequency of disturbances and age of each habitat unit from its disturbances. Then if intermediate disturbances enhance
habitat diversity, it is prerequisite for proving thefollowing two aspects:
Biological diversity is maximized by spatial
heterogeneity, defined as “spatial heterogeneity
hypothesis”; andThere are disturbance regimes, which maximize
biological diversity in temporal heterogeneity ofhabitat conditions, i.e., disturbance intensity andfrequency and age of each habitat unit, definedas “temporal heterogeneity hypothesis”.
Our approaches to prove these hypotheses canbe explained. Spatial heterogeneity hypothesis canbe proved by analyzing whether resultant habitat
diversity, which maximizes biological diversity,
is characterized by intermediate disturbances.
Temporal heterogeneity hypothesis can be provedby developing a series of special distributions ofeach habitat unit and its age and analyzing conditions that maximize biological diversity. We identify spatial heterogeneity hypothesis and temporal
heterogeneity hypothesis are substantial components of habitat diversity hypothesis.
4

AN ATTEMPT TO ANALYZESPATIOTEMPORAL PATTERNSIN THE TENRYU RIVER

In order to prove the habitat diversity hypothesis
discussed above, we started a case study in July2012 in a middle reach of the Tenryu River Japan,of which the riverbed is likely to move by a certain discharge. There is a similar case study, whichanalyzes spatiotemporal patterns using intervalrecording cameras in the Tagliamento River Italy(for example, Arscott 2002). This study is effective
to gain plenty of qualitative data through photos
but cannot quantify quantitative data, e.g., areaof changing habitat and deposition and erosion
processes. In the Tenryu River, in respect to the
Tagliamento study, photogrametric mthods areused as a challenge to solve the problems. Data
has been collected on spatiotemporal patterns byseveral interval recording cameras (hourly) placed
at 60 m high from the riverbed in the center ofthe river corridor. Several camera-recording cantransform photos into 2 D, i.e., ortho data, and
3 D data, enabling to quantify the spatiotemporal patterns including erosion and deposition processes, using photogrametoric methods.
Figure 12 shows a view of recorded photo data
capturing upstream of the Tenryu River in (a)and transformed results for analyzing spatiotemporal patterns in (b) and (c), where the camera
view is transformed into 2 D and 3 D data. This
article is kept up to introduce our attempt to be

Figure 12. Recorded photo data taking upstream of the Tenryu River and transformed results for analyzing spatiotemporal patterns.

1565made, methodologies and results of which will bereported in another article.

5

CONCLUSIONS

The review revealed that spatiotemporal patterns,
determined by flow and morphological regimes,
should be integrated into restoration projects
depending on its scales and objectives. We propose the habitat diversity hypothesis as a different approach from the intermediate disturbance
hypothesis, which explains biological diversity
composed of two aspects: spatial heterogeneity
hypothesis and temporal heterogeneity hypothesis.
We started a case study in the Tenryu River via
interval-recording cameras. This study can be a
new approach to analyzing spatiotemporal pattersof habitat structure quantitatively, through which
spatial and temporal patterns are expected to beinter-woven.

ACKNOWLEDGEMENTS
This study in the Tenryu River was supported bynumerous people and organizations. Acknowledgements are given particularly to the Kakegawa
electronic office of the Chubu Electronic PowerCo. Inc., Hamamatsu branch office of the C-tech
Corporation, Tenryu River Fisheries Cooperative,
Hamamatsu Office of River and National Highwayof the Ministry of Land, Infrastructure, Transport
and Tourism, and IDEA Consultants, Inc.

REFERENCES
Arscott, D., Tockner, K., Nat, D., & Ward, J. 2002. Aquatic
Habitat dynamics along a Braided Alpine River Ecosystem (Tagliament River, Northeast Italy), Ecosystems 5,
802–814, DOI: 10.1007/s10021-002-0192-7.
Baptist, M.J., & Mosselman, E. 2002. Biogeomorphological modelling of secondary channels in the Waal river.
In: D. Bousmar & Y. Zech, (eds.), River Flow 2002
Symposium: 773–782, Louvain-la-Neuve, Belgium.
ChikimaRiver
EcologicalResearch
Group,
Nakamura K., & Kawaguchi K. 2010. The status andoutcomes of the Chikuma River Ecological Research,
Riverfront 2010 Vol. 68, 8–13 [all in Japanese including the title].
Connel, J.H. 1978. Diversity in Tropical Rain Forests
and Coral Reefs, High diversity of trees and corals
is maintained only in a nonequilibrium state, ScienceVol. 199, 1302–1310.
Formann, E., Habersack, H.M., & Schober, St. 2007.
Morphodynamic river processes and techniques forassessment of channel evolution in Alpine gravel bed
rivers, Geomorphology 90 (2007) 340–355.

Institute for Inland Water Management and Waste Water
Treatment (RIZA), 2001. Guidelines for rehabilitationand management of floodplains Ministry of Transport, Public Works and Water Management, RIZA
report: 2001.059, ISSN 1568-234X.
Ishikawa, T., Shimizu T., & Niimura N. 2010. Establishment of countermeasures for nonnative plants andriparian forest management to reduce maintenancecost in river management, Chikumagawa River Office,
Hokuriku Regional Development Bureau of Ministryof Land, Infrastructure, Transport and Turism,
Japan [all in Japanese including the title], found as of
31 December 2012 on the website: www.hrr.mlit.go.jp/
library/kenkyukai/h22/kankyou/11.pdf.
Jans, L., Backx, J., Greijdanus-Klaas, M., deJonge, J., van der Meij, V., Oosterbaan, J., van der
Scheer, A., & Schropp, M. en M. van Wijngaarden, M.,
2001. Monitoring Nevengeulen. Integrale Jaarrapportage 1999/2000. RIZA Werkdocument 2001.062x.
RIZA, Lelystad.
Kantoush, S.A., Sumi, T., & Takemon, T. 2011. Lighten
the load, International Water Power & Dam Construction, May, pp. 38–45.
Karr, J.R. 1981. Assessment of biotic integrity using fish
communities. Fisheries 6, 21–27.
Karr, J.R. & D.R. Dudley. 1981. Ecological perspective
on water quality goals. Environ. Manage. 5, 55–68.
Kondolf, G.M., & Minear, J.T. 2004. Coarse Sediment Augmentation on the Trinity River Below Lewiston Dam:
Geomorphic Perspectives and Review of Past Project.
Kumagai, H. 2009. Approaches to ecological restoration by artificial floods from the Managawa dam [inJapanese], Kinki Regional Development Bureau of
the Ministry of Land, Infrastructure and Transport,
found as of 31 December 2012 on the website: http://
www.kkr.mlit.go.jp/plan/happyou/thesises/2009/
pdf02/08.pdf.
Matthaei, C.D., Peacock, K.A., & Townsend, C.R. 1999.
Patchy surface stone movement during disturbance ina New Zealand stream and its potential significancefor the fauna, Limnology and Oceanography 44(4),pp. 1901–1102.
McBain & Trush, Inc. 2000. Trinity river restoration program, summary of the United State Secretary of theInterior Record of Decision.
Mohl, A. 2012. LIFE River restoration projects in Austria,
found as of 26 December 2012 on the website: http://
www.biomura.si/prenosi/Izvananje%20projekta/
LIFE%20River%20restoration%20projects%20
in%20Austria/Life%20Riever%20restoration%20
projects%20in%20Austria.pdf.
Nakamura, K., Tockner, K., & Amano, K. 2006. Riverand Wetland Restoration: Lessons from Japan, Bioscience Vol. 56 No. 5, 419–429.
Ock, G., Muto, Y., Sumi, T., & Takemon, Y. 2010. Rolesof Riffle and Pool Structure in Particulate Organic
Matter Dynamics in the Downstream Reaches of Dam
Reservoirs, Annuals of Disaster Prevention ResearchInstitute, Kyoto University, No. 53 B, 773–782.
Ock, G. & Takemon, Y. 2011. Relation of Hydrogeomorphology of Gravel Bar in Particulate Organic Matter
Dynamics in Braided Alpine River, Annuals of Disaster Prevention Research Institute, Kyoto University,
No. 54 B, 727–733.

1566

Parsons, M., Thoms, M., & Norris, R. 2001. AustralianRiver Assessment System: AusRivAS Physical Assessment Protocol, National River Health Program, Environmental Australia.
Peter, A. 2006. Rehabilitation- to What Extent, andWhy?, Eawag News 61e. Flood Protection and Rehabilitation—New Direction for Our Rivers.
REFORM, 2012. River Drau—Austria, Flagship restoration measure, found as of 26 December 2012 on
the website: http://www.reformrivers.eu/river-drau%E2%80%93-austria-flagship-restoration-measure.
Rohde, S. 2004. River Restoration: Potential and limitations to re-establish riparian landscapes. Assessment &Planning., a dissertation submitted to the Swiss Federal Institute of Technology Zurich for the degree ofscience.
Rohde, S. 2006. Widening as a Rehabilitation
Measure, Eawag News 61e. Flood Protection andRehabilitation —New Direction for Our Rivers.
Sakamoto, H., Nakamura, J., Sumi, T., & Azami, K.
2006. Planning and evaluation method for “flushingflow” under the trial of flexible operation of Managawa dam, Kasen gijutu ronbun shu [in Japanese],
Vol. 12, 271–276, Japan Society of Civil Engineers.
Shimatani, Y. 2003. Conservation and Resroration ofRiver Environment, Ecology and Civil Engineering
5(2), 223–240 [in Japanese with English abstract].
Sumi, T., & Kantoush. S.A. 2010. Integrated Management of Reservoir Sediment Routing by Flushing,
Replenishing and Bypassing Sediments in JapaneseRiver Basins, 8th International Symposium on Ecohydraulics, CD-ROM.
Takemon, Y. 1997. Management of biodiversity in aquatic
ecosystems: dynamic aspects of habitat complexity
in stream ecosystems. In: (ed. by Abe T., Levin S., &Higashi M.) Biodiversity: An Ecological Perspective.
Springer, 259–275.

Takemon, Y. 2007. Ecology and Civil Engineering asa science of habitat, Ecology of Civil Engineering.
10(1), 41–46, Japan.
Takemon, Y. 2008. Spatial distribution patterns of allochtonous and autochtonous benthic particulate organic
matter on the riverbed of a mountain stream in Kyoto,
Japan, Water Down Under 2008, pp. 2393–2403.
Townsend, C.R., Scarsbrook M.R., & Doledec S. 1997.
The intermediate disturbance hypothesis, refugia andbiodiversity in streams, Limnology and Oceanography 42, pp. 938–949.
Unno, S., Saida, K., Ise, T., Suetsugi, T.,
Fukushima, M.K., & Fujimoto, M. 2006. Change of
biological community and bed topography after thegravel-bar restoration work on the Nagata district in
the Tama River, Ecology and Civil Engineering 9(1),47–62 [in Japanese with English abstract].
U.S. Fish and Wildlife Service. 1981. Standards for thedevelopment of habitat suitability index model for use
in the Habitat Evaluation Procedures, USDI Fish andWildlife Service, Division of Ecological Services. ESM
103.
U.S. Fish and Wildlife Service. 1989. Physical Habitat
Simulation System Reference Manual Version II.
Instream Flow Information Paper No. 26.
US Secretary of the Interior. 2000. Trinity river restoration program, Summary of the US Secretary of theInterior, Record of Decision.
Wilson, J.B. 1990. Mechanisms of species coexistence:twelve explanations for Hutchinson’s ‘paradox of theplankton’: evidence from New Zealand plant communities. New Zealand Journal of Ecology, 13, 17–42.
Wright, J., Sutcliffe, D., & Furse, M. 2000. Assessing thebiological quality of fresh waters: RIVPACS and othertechniques, Freshwater Biological Association.

1567