The Water Balance of the Hongru River BasinHongyu Chen
The Huaihe River Commission of the Ministry of Water Resources
No.41 West Fengyang Road, Bengbu, 233001, P.R.China
Email: Hychen1@hrc.gov.cn
Abstract
This research focused on water balance in the Hongru River Basin. It would be noted that thestudy area was characterized by its precipitation, runoff and evapotranspiration, and their temporal andspatial distributions are discussed. Finally, a water resources development strategy was presented basedon the analysis on water balance, the strategy could ensure the water environment sustainability.
Key word: Hongru River, water balance, precipitation, and runoff

1.Introduction
The Huaihe River Basin (HRB) waslocated in the transitional zone of southern tonorthern climate in China. The Hongru River
Watershed (HRW) was one of the largest
branches of HRB, and it played an importantrole in studing the water balance of HRB. In
HRW, the hydrological observation started
from 1956, and the precipitation, discharge andopen water evaporation were recorded. In thispaper, The physical– geographical description ofHRW was presented. Temporal and spatial
distribution of the precipitation, discharge andevaporation was the most important research
objective in the water balance study. So far, wehave been made to estimate the temporal andspatial distributions of precipitation, runoff
evaporation were estimated. The objectives ofthis study were as follows:.to analyses the series of the discharge,
rainfall and evaporation.
.to estimate mean precipitation, runoff andevaporation, in HRW and to analyses waterbalance components of the basin.
.to analyses temporal and spatial
distribution characteristics of precipitation andrunoff in HRW.

2.study area and methodology
The Hongru River was originated from theFuniu Mountains (Fig. 1),
where the highest elevation is500mroughly. It was located in northwest of theHuaihe River Basin, between 113º38΄-115º30΄N and 32º30΄-33º30΄E, flowed to the HuaiheRiver main channel at the boundary between
Henan and Anhui Provinces. It is one of thelargest branches of the Huaihe River Basin, witha drainage area of 12,380km2, a length of 325km.
The terrain in the northwest was mountains andFig.1 location of Hongru river basin
hilly, and in the remaining part was plain The
proportion of mountains, hills, plains andlow-lying areas to the total areas were 15%, 19%,52% and 16% respectively. In this research, total
25 rain-gauges daily rainfall series and 8 stations
daily discharge series were applied. All of thestations were set up at the places for the sakeof spatial representative,

easy for guarding,data recording and repairing..
the following general equation of waterbalance in HRW was as equation (1):P=Q+E±ΔW±ΔV(1)
where P was the total precipitation in HRW,.
Q was the runoff of HRW, E was the total landevaporation,ΔW was –water withdrawal, AndΔV was stored water of reservoirs and lakes.
In large river basin, the water balance
equation was used for quantitative evaluation ofbasin resources and for water project planning.
For along time interval,
the equation(1)would be rewritten in equation (2) and (3).
P=Q+E±ΔW(2)
R= Q±ΔW(3)
where:

were scarce in winter and spring, and abundantin summer and autumn in HRW.
Corresponding to the year with anexceedance probability of 90% (P), annual
percipitation(mm)R was –the total runoff.
All the data series were from 1956 to 2000.
The investigated monthly data series ofagricultural, industrial and domestic watersupplies, collected by the Hydrological Bureauof Henan Province, were also used to the water
budget analysis. A conceptual basin hydrologicalmodel was built to analyze the precipitation
distribution among the runoff, evapotranspiration,basin storage change and water supplies. The
time series of the water budget components wereanalyzed also. Some parameters of thehydrological model, such as the maximum soil
moisture (SM), field capacity (Fc), and so on,were estimated by the method of “trial-anderror”. The efficiency coefficient of simulated
runoff series to natural runoff series, which was
the sum of the measured discharge, watersupplies, the diverted water to outside of thesub-basin, and etc., was selected as the objectivefunction of the modeling.

160140120
1008060
40
20012345678

9 10 11 12monthFig.2 the monthly variation of precipitation

3.results
70runoff(mm)6050403020100123456789 10 11 12 monthFig.3 the monthly variation of runoff
value(mm)According to the analyzed result, showing
the long-term average annual precipitation of
Hongru River Basin was 915mm(or 11.3 ×109m3) , the runoff 244 mm(or 3.02×109m3) andthe evapotranspiration 650 mm(or 8.30×109m3).
In the sub-basin, the temporal and spatial
distributions of precipitation and runoff wereuneven. Since 1956, annual precipitation andrunoff data had been obtained. The largest andthe smallest annual precipitation were 1379mm
and 483mm respectively, and the largest and thesmallest annual runoff were 657.2mm and34.1mm respectively, so differences ofprecipitation and runoff between different years
were large, and the largest values were morethan 2.9 and 19.3 times of the smallest values
respectively in Hong river basin.
The spatial distribution of the precipitation,runoff and open water evaporation was observedin HRW. Precipitation and runoff in the south
were larger than that in the north, and thevalues in the mountains were larger than that in
the plains. The precipitation in the upstream
was 900-1200mm and the runoff 300-400mm.
The maximum of precipitation and runoff weremeasured in the mountains area.
Both of temporal distributions of the
precipitation and runoff were uneven. In a year,
more than 50% of them concentrated in summer
from June to August. Fig.2 and Fig.3 were themonthly variation of precipitation and runoff.
The maximum and minimum of precipitation
were in July and December respectively, and themaximum and minimum of runoff were inAugust and January respectively.
Fig.4 showed that precipitation and runoff

450runoff

precipitation

400
350
300
250
200150100500springsummerautumnwinterseasonFig.4 the seasonal variation of runoff
precipitation of HRW was 89.1mm(or 1.10 ×109m3), the runoff 47.5mm(or 0.59 ×109m3),which was 9.7% and 19.5% of theaverage annual precipitation and runoff
respectively. Analyses were made with thesedata to understand the trends of precipitation

350

6 3

water supply(10 m )and runoff in this watershed. The preliminary
analysis showed that there was a tendency of
decrease about precipitation and runoff during
1956-2000.The long-term annual precipitation
and runoff over 21 years (1980-2000) wassmaller than that of over 24 years (1956-1979).
The long-term average agricultural,industrial and domestic water supplies were 116×106m3, 3×106m3, and 2×106m3 respectively.
The agricultural water supplies accounted for
85% of total water supplies roughly. Fig.5
showed that the trend of water supplies wasincrease, especially after 1980 due to the quickly
local economy development and the increaseof population. Therefore, the conflict between
water demand and water supply was graduallyserious.

300
250
200
150
10050

1996

1992

1988

1984

1980

1976

1972

1968

19641960

1956

0yearFig.5 annual series of total water supply
Finally, a general water resources
development strategy for HRW was presented
based on the water balance analysis. HuaiheRiver Basin faced water shortage problems inmany places due to rapid development in termsof population growth and industrialization. The
water consumption would continuously increase.
The objective of development strategy was toensure the water environment sustainability.