Research Trends and Results

About the future water resource management
considering the climate change- Evaluation of the analysis technology aiming the appropriate use and maintenanceof the underground waterKAWASAKI Masaki, HeadNISHIMURA Sorin, Senior researcher
River Department, River Management and Dam Division（Key words）Climate change, Underground water, Water resource management, Flow analysis, Water balance analysis

1. Introduction
To create sustainable and powerful national land andlocal area, it is imperative to secure the stable and goodquality water supply based on the health and sane water
recycle. In particular recently, as it is estimated to see
increasing drought risk due to climate change, increasingwater demand due to global population increase andfurther tough competition on the water business, under
the circumstance future tight water demand and supply isconcerned, we have to proceed on working toward
upgrading the water resource management
Specifically, we are required to achieve integrated
water resource management to use various water
resources including underground water and rain water on
effectively utilizing respective characteristics going awayfrom the conventional water resource management basedon the surface stream water.
2. Process and task concerning the underground water
management
Underground water has been broadly utilized for the
daily life water and various purposed as good quality,
convenient and cheep water resource.
However, as too much water intake caused by theindustrialization has resulted in underground water
obstruction such as ground sinking, we have seen aprocess to convert the resource to the surface stream
water on restricting the water intake of the undergroundwater by the Industrial Water Act.
Further, to the character of the underground water as a
private property attached to the land, with the recent pointof view that the underground water is a significant factor
to compose the water recycle, it is required that the public
nature of the underground water prevails as thesocially-accepted idea.
Accordingly, activated use of the underground water is,
still securing the underground water appropriately, a
conversion of the paradigm, and it is required to achieve
reliable quantitative research result that contributes tosuch a breakthrough, make concepts and further to makea new rule.
On the other hand, as for the analysis of theunderground water, analysis theory and numeric value
analysis technology to resolve it are already established.
However, there is a problem of lower accuracy in theanalysis since the given condition of such an analysis
such as the data of the underground water level, water
intake volume, earth quality condition were not grasped
sufficiently.
3. Outline of this researchThis research has adopted the watershed of theChiyogawa river, the first class water system as the casestudy watershed so as to construct both the flow analysis
model and water balance analysis model and predict thefuture on the effect that the climate change gives to thesurface stream water and underground water, in which westill proceed on the analysis.
In the flow analysis, we have supposed a model with apoint of view to grasp and make visible the undergroundwater flow in the watershed as precisely as possible. Thisis because we are to submit the result for the purpose of
making a common concept among concerned parties andfor the judgment whether or not to expect theunderground water as an alternative water resource at thetime of the drought, thus to make it the analysis
technology to support the general water resource
management in respective area. We have made thismodel a water recycle model using the “integrated water
recycle simulator” that is able to analyze the surface
stream water and underground water perfectly all
together.
For the water balance analysis, we have supposed amodel in a viewpoint of the convenience. This is for the
purpose of making it a macroscopic analysis technologythat contributes to grasp the long-term wide spread areachange of the water balance that can be submitted to thediscussion of what is the nation wide water resource
management including the underground water. We havemade this model a tank model composed of the damwatershed, residual watershed and underground waterbasin.
4. Future perspective
We are currently collecting data of the undergroundwater level in the country together with the above
analysis. From now on, we would like to make ananalysis of the trend of recent underground water leveland future prediction of the effect on the surface stream
water and underground water caused by the climatechange in a nationwide view so as to study what shouldbe the future water resource management considering
also active utilization of the underground water.
【Reference】
1) Study group “What should be the integrated water resource
management considering the risk by the climate change andso on”
http://www.mlit.go.jp/tochimizushigen/mizsei/07study/07study.
html2) TECHNICAL NOTE of NILIM No.322 Study on theunderground water model
http://www.nilim.go.jp/lab/bcg/siryou/tnn/tnn0322.htm
3) TOUSAKA Hiroyuki: Mathematics of the ground area water
recycle，University of Tokyo Press 2006.12