Monthly Water Budget of Small Basin in Northern of Loess Plateau,China

Dec. 2010Journal of Northeast Agricultural University (English Edition)Vol.17 No.4 14.19Monthly Water Budget of Small Basin in Northern of Loess Plateau,ChinaHUANG Jinbai', HINOKIDANI Osamu', YASUDA Hiroshi', Kimura Reij', and ZHENG Jiyong*' College of Water Conservancy and Building Engineering, Northeast Agricultural University, Harbin 150030, China'Faculty of Engineeing, Tottori University, Ttr, 680-8552, Japan' Arid Land Research Center, Tottori University, Tottori, 680-0001, Japan* Soil and Water Conservation, Chinese Academy of Sciences & Ministry of Water Resources P.R China, Yangling 712100, Xian, ChinaAbstract: The objective of this study was to analyze the water budget of a small basin in the northern of Loess Plateau. A smallbasin, Liudaogou in the northerm Loess Plateau was chosen as the study area. The numerical calculation of surface runoff was appliedto results of the field survey, and components of monthly water budget were estimated. The unit area of I km2 was selected as theindex area for the estimation. A component of habitant water consumption was added to the water budget to consider the contributionof human activity. Results indicated that the water storage was negative in May, June and July while the annual amount wasapproximately 0.0. Evaportanspiration attained maximum in August and its annual total accounted for 74.2% of annual precipitation.Results of this study are significant for the sustainable water conservation and utilization in the northem of Loess Plateau whereannual water resources are relatively deficient.Key words: Loess Plateau, Liudaogou Basin, water budgetCLC number: TV121; TV123Document code: A Article ID: 1006-8104(2010)-04 0014-06Sustainable agricultural development is hardly guaran-Introductionteed by the limited water resources.The water budget at the earth's surface is complexChinese Loess Plateau, as a vast semiarid region and and dynamic. The relationship involves interactionshigh risk region of desertification, has widely been ofamong atmosphere, surface, soil, plant and ground-concem not only in China but also in the world. In thewater. Main components of the hydrologic circle areprocess of desertification, the serious soil erosion hasprecipitation, runoff, infiltration and evapotranspira-occurred in Loess Plateau since the 17th centuryl2. In tion'+6!. Analysis of the water budget is the basis forthe northem Loess Plateau, the tendency of desertifica- realizing the scientific evaluation and appropriatetion has become more severe than in the southernallocation of the water resources in a basin'".region of Loess Plateau due to the long term water andwind crisscross erosion as well as low precipitation.Study AreaThe average annual precipitation of this region is only400 mm with apparent seasonal fluctuation and itLiudaogou Basin was chosen as the study locationresults in the deficiency of available water resources'!.and it was located at the northem Loess Plateau (110°中国煤化工Received 19 August 2010Supported by JSPS Core University Program, Japan; CAS "Westem Light" (2006YB0JMYHCNMHGE-mail: buangjinbai@HUANG Jinbai(1974-). male, Ph. D, associate professor, engaged in the research ohotmail.comE-mail: xuebaoengish@neau. edu.cnHUANG Jinbai et al. Monthly Water Budget of Small Basin in Norhermn of Loess Plateau, China.15.21'-1 10°23' E longitude and 38946'-38051' N lati-budget formula:tude, area: 6.89 km') (Fig. 1). Average annual rain-OW=P- -R- ET-U(1)fall is 430 mm and more than 70% of the total isreceived in the rainy season from June to Septem-Where, P is precipitation; R is runoff which includesber. Annual potential evapotranspiration generallysurface runoff and groundwater (GW) outflow; △W isexceeds 1 000 mm. The rigorous water and windchange of water storage; ET is evapotranspiration; U iscrisscross erosion causes severe degradation of thehabitant water consumption. The general distributionsecological environment and high risk of the desertifica-of water components of the water budget in the studytion. The population of Liudaogou Basin is 533 andlocation can be depicted by a schematic illustrationit has remained stable in recent years. The irrigated(Fig. 2). As an index, the water budget for the unit area,farmland area is 20.6 hm2. Vegetation cover only1 km', was evaluated in the present study.accounts for about 25 % of the total basin area.The field observation was conducted at the studyComponents of monthly water budgetarea mainly on rainfall, groundwater level and soilMonthly water incomewater content. Arrangement of the field observation isIn the closed basin, monthly water income refers toshown in Fig. 1.the precipitation received in every month. Accordingto rainfall data from 1956 to 2007, monthly rainfall110*21'Small rervoirdistribution was estimated as shown in Fig. 3.Dum-RunoffSurface runoffThe surface runoff was estimated by using a numericalWell No2calculation model which was developed by kinematicwave theory and channel networks. The study area,+ 38946'o Kainfll* Soil water contontLiudaogou Basin, was lumped to channel networks in: Grudwuerteve Groundwaer flowthe previous study (Fig. 4)"0.Fig. 1 Location of Liudaogou BasinThe validity of this runoff calculation mode1 wasverified by numerical simulation of the observed dataMethodology(observation point, Fig.1). The simulated result isshown in Fig. 5. Based on numerical calculation resultsEquation for water budget estimationof surface runoff from 2005 to 2008, the annual runoffConsidering habitant water consumption in the studyrate was estimated to 12%. Its monthly distribution isarea, a new factor U is added to the common water shown in Fig. 6.( Precipitation )↓(Evapotranspiration( Water storage)( RunoffWater uiztion「厂↓「Evaporation TranpirationSoil water change(Gw chang) Surface中国煤化工)rigatioYHCNMHGFig. 2 Schematic ilustration of water budgethttp: /pubish.neau.edu.cn.16.Joumal of Northeast Agricultural University (English Edition)Vol. 17 No.4 2010carried out (Fig. 1). GW flow occured at the phreatic150.00zone. The groundwater outlow was relatively stable合120.00and did not show distinct change due to seasonal90.0060.00changes. However, in winter, as the upper ground was30.00。[afrozen, GW outflow seasonally ceased from December亘盘是姜皇息京芝昏莒莒莒to the end of February. Liudaogou Basin can be treatedas a homogeneous model in hydraulics research due toMonthits uniform ground condition!". Therefore, GW flow isFig. 3 Monthly rainfall distribution (Rainfall data: 1956-considered to be uniformly generated from each of the2007)tributary. Based on the observed results, monthly distri-SPbution of GW outflow was estimated as shown in Fig, 7.Rainfall自6000 [5 00040003 0000亏20001 0005，Fig. 4 Model lumping of the study areaFig. 7 Distribution of monthly GW outflow (unit area: I km)0.300 Tr "TT 'Monthly change of water storage0.8In the study area, deep GW generally lies at depth巨0.180■ Rainfall.6兰of dozens of meters or even over a hundred meters-O-low0.120 F-C-lowfrom the ground surface. The deep GW cannot be0.0603.2号effectively recharged from the rainwater infiltrationl!"].4.0The annual water storage was mainly dependent onvariation of the soil water content and change of theTimeshallow GW.Fig. 5 Simulated result of the surface now (23-24 Sep.2008)Monthly variation of soil water contentThe soil water content data was obtained from pre-20 0vious research activities at the same study location'"3l.会自16000The soil water observed point is shown in Fig. 1. In包800the study area, the evapotranspiration can impact on4 000infiltration to the maximum depth of 60 cm from theground surface and the soil water content remainsrelatively stable below this depthl1]. The observationFig. 6 Distribution of monthly surface runoff (unit area: 1of the soil water content was conducted at the depth ofkm)4, l0, 26, 34, 42, 50, 58, 66 and 100 cm, respectively.The:vater content wasGroundwater outlowestin中国煤化工i data and its resultThe observation of the groundwater (GW) flow wasis shTYHCNMHGE-mail: xuebaongish@neau.edu.cnHUANG Jinbai et al. Monthly Water Budget of Small Basin in Northem of Loess Plateau, China.17(well No.2 in Fig. 1). GW in this well belongs to thephreatic water. Amount of the diurnal domestic water0.012 [0.008 twas 200 m' and increased to 300 m' in summer from0.004 tJune to August. The monthly domestic water for unit0.00●area was estimated as shown in Fig. 11. .-.0080816000写14000MonthFig. 8 Monthly variation of soil water content10 000Monthly GW change4 000The observation of shallow GW was carried out on2 000a point (well No.1, Fig. 1). The mean monthly GWchange during the observed time (May 2005-Dec.2007) is shown in Fig. 9. The figure represents GWchange is approximately 0 at yearly beginning andFig. 10 Distribution of monthly rrigation waterend.1 6001 4000.20 r1 2000.10-1 000Hrg -0.10-800-0.20-600-0.3040-0.40200Mont自岔皇姜皇身巨皇宫吉差宫Fig. 9 Monthly GW changeFig. 11 Distribution of monthly domestic waterWater consumptionThe water consumption in Liudaogou Basin includesEvapotranspiration (ET)domestic water and irigation water.Monthly ET was calculated by a reference crop ETIrigation waterwhich has already been validated to be adequate forThe irrigation water was provided by the two re- calculation of ET over the grassland in Liudaogouservoirs, large and small as shown in Fig. 1. Amount Basin's .of irrigation water withdrawal was approximately0.4080(R,- G)+y ._37estimated by the change of the water level in the”7+273 ulere)two reservoirs. The time for irrigation water estima-ET=O+y(1+0.34u)(2)tion was from 2006 to 2008. The monthly distribu-tion of irigation water for the unit area is shown inWhere, ET。is the reference crop ET (mm+h'); s isFig. 10.the slope of the saturation vapor-pressure at air temDomestic waterperature (kPa."C); R, is net radiation (MJ.m°.h');The domestic water normally includes water supplyy is the中国煤化工); G is the soilfor residents and cattle. The domestic water is suppliedheat fYHC N M H Gd vapor-pressureby an artesian well at the upstream of Liudaogou Basinat air temperature (KPa); e。IS the actual vapor-pre-http: /publish.neau.edu.cn18.Joumal of Northeast Agricultural University (English Edition)Vol. 17 No.4 2010ssure (kPa); T is the mean hourly temperature (C); u isthe average hourly wind speed at height of2 m (ms').Results and DiscussionThe average height of the grass is assumed to be 15 cm.The amount of annual ET over grassland is estimatedResultsto account for 69.7% annual precipitation. ET overIndex of monthly water budget is shown in Fig. 13.grassland is generally lower than that of the farmland,Results of each component of monthly water budgetthe nudation and the shrub land. Results of ET whichare listed in Table 1.were simply estimated over grassland must be adjustedtowards estimating ET over various vegetation forms.MonthAnoual ET accounts for 74.2 % of annual precipitationwhich was adopted for data adjustment!'9. The esti-mated results of monthly ET distribution is shown in息8EPrecipitationC.Fig. 12.20●--RunofT90「0F30 F尊-68E-Watrsorare.s50 -100.00 [75.0020 F4.001oanwlha3.00 F --Water uilization.身岔是姜夏自宫皇身宫差莒Fig. 12 Monthly ET distributionFig. 13 Monthly distribution of the water budgetTable 1 Results of monthly water budget (unit area: 1 km'; unit: 10' m')ItemsWT→SurfaceGWTSumD.WLWGWCs.W2.520.000.880.01.253.77.8Feb.3.620.801.705.022.411.024.2631.443.245.222.430.850.621.4710.200.6010.8015.326.644.626.15.16- 41.20un.49.093.0312.65 .1.290.211.50-87.67-5.10-92.7733.3ul.11.3412.9417.96 .1.342.203.54-47.875.61- 42.26ug.119.7815.37.0520.421.512.8516.5610.0526.6178.9Sep.52.619.714.480.251.1019.500.5020.0051.9)et.21.524.374.659.020.050.9349.28-5.5043.7829.7Nov.7.804.1515.80-2.6013.200.1ec..63882.622.0E43093.90319%10021.803.90中国煤化工-74.2IY片CNMHGD.W-Domestic water; L.W.Irrigation water, S.W-Variation of soil water content; GWC-urounuwac Cnang.E-mail: xuebaoenglish@ neau.edu.cnHUANG Jinbai et al. Monthly Water Budget of Small Basin in Northem of Loess Plateau, ChinaPlateau [C]. Proceeding of the 8th International Conference onDiscussionHydro-Science and Engincering, 2008: 129-130.The surface runoff mainly occurs in rainy seasons and4 Kazmann R G. Modem hydrology [M]. New York, U.S.A: Harperthere is no surface runoff generation except the period& Row, 1965: 3-9.from May to October. There is no runoff through-5 Eagleson P. Dynamic hydrology [M]. New York, US.A: McGrawout winter. After the start of vegetation period, ETHill, 1970: S-10.gradually increases which results in water storage de-6 Huang M B, Shao M A,Li Y s. Comparison of a modifiedcreases distinctly. GW consumption attaints the maxi-statitical-dynamic waler balance model with the numericalmum in June and it results in the lowest water storagemodel WAVES and field measurements [小. Agricultural Water(the maximum negative). ET decreases gradually afterManagement, 2001, 48: 21-35.August while water storage shows increasing tendency7 Zhu X J, Wang Z G, Xia J. Basin level water balance analysis studyafter June. The monthly water storage remains positivebased on distributed hydrological model-case study in the Haiheexcept in May, June and July. GW is effectively re-River Basin []. Progress in Geograpby, 2008, 27(4): 23-27. (incharged in the periods from August to October andChinse)from February to March. The water utilization remains8 Jiang N, Shao M A, Lei T w, et al. Spatial variability of soil incomparatively stable except period from April tofiltration propertics on natural slope in Liudaogou catchment onAugust and the maximum occurs in July. Runoff, ETLoess Plateau小Joumnal of Soil and Water Conservation, 2005,and water consumption increase markedly in July and19(1): 14-17. (in Chinese)August.9 Fan J, Shao M A, Wang Q J. Soil cater testoration of alfalfa land inthe wind-water erosion cisscross region on the Loess Plateau [0].ConclusionsActa Agrestia Sinica, 2006, 13(3): 261-264. (in Chinese)10 Huang J B, Hinokidani O, Yasuda H, et al. Study on characteristicsMonthly amount (annual) of water storage is appro-of the surface flow of the upstream region in Loess Plateau [小ximately 0. Runoff (surface and GW), water con-Annual Jourmal of Hydraulic Engineeing, JSCE 2008, 52: 1-6.sumption and ET account for 21 .8%, 3.9% and 74.2%1 Zheng J Y, Shao M A, Li s Q.Variation of the hydraulic charac-of the total water budget, respectively.terstics of the soil profile in water-wind erosion crisscross regionET is the most predominant component of water[]. Transactions of the CSAE, 2005, 21(11): 64-66. (in Chinese)expenditure.12 Fan J. Study on the soil water dynamics and modeling in water-wind erosion cisscross region on the Loess Plateau [D]. Beijing:ReferencesInstitute of Soil Science, CAS, 2005: 30-75. 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