Influences of Water Conservancy and Hydropower Projects on Runoff in Qingjiang River Upstream Basin

Journal of Earth Science, Vol. 27, No. 1, p. 110–116, February 2016 ISSN 1674-487X Printed in China DOI: 10.1007/s12583-016-0640-5

Yi Sun1, 2, Junwei Wan*1, Songyuan Yang3, Xinghua Xue2, Kun Huang1 1. School of Environmental Studies, China University of Geosciences, Wuhan 430074, China 2. School of Biological Science and Technology, Hubei University for Nationalities, Enshi 445000, China 3. Enshi Autonomous Prefecture Hydrographic and Water Resources Survey Bureau, Enshi 445000, China

ABSTRACT: Hydrological data on the Upper Qingjiang River from 1960 to 2012 document trends of runoff caused by hydropower engineering projects and long-term changes in rainfall. Annual runoff correlates strongly with annual precipitation, but is significantly reduced after reservoir construction compared to earlier values. Comparisons of intense, pre- and post-construction rainfall events suggest that the Chebahe and Dalongtan reservoir projects respectively clips the magnitude of the flood peaks and delays runoff delivery. KEY WORDS: Qingjiang River, water conservancy, hydropower project, runoff characteristics, hydrological response, rainfall intensity.

0 INTRODUCTION west to east through Lichuan, Enshi, Xuanen, Jianshi, Badong, Precise runoff calculations are essential to flood forecast- Changyang, Yidu, ultimately joining the Yangtze River at Lu ing. Many studies have demonstrated that climate change Town. The drainage area is 16 700 km2, and along its total (Zhang Y et al., 2014; Zhang S Q et al., 2013; Crosbie et al., length of 423 km the river falls 1 430 m. Paleozoic and Meso- 2010; Mileham et al., 2009) and human activities, especially zoic carbonates underlie about 70% of the Qingjiang River Ba- water conservancy and hydropower projects, influence runoff. sin, and the principal geomorphic features are peak-cluster de- Several studies (e.g., Pan et al., 2016; Hasenmueller and Criss, pressions and peak-cluster trough valleys. Surface karst depres- 2012) show that annual runoff in river basins is correlated with sions, funnels, rift valleys, trough valley slopes, karst caves and the amount of precipitation received. Other research shows that underground rivers are well developed (Wang and Wan, 1999; human activities are more important (Ling et al., 2014; Zhou et Shen, 1996). al., 2012; Xu, 2011; Dobrovolski, 2007; Su et al., 2007; Is- Qingjiang River can be divided into three sections: a maiylov and Fedorov, 2001). For example, several studies on headwater section that extends from the divide to Enshi city, a rainfall and runoff trends conclude that annual rainfall has no middle section that extends from Enshi to Longzhouping Town obvious change on runoff, while great changes are caused by in Changyang County, and a lower section stretching from water conservancy projects (Huang et al., 2002; Liu and Li, Longzhouping to the estuary. This paper uses the Enshi Hydro- 2002; Ren et al., 2001). This paper uses long-term data on flow logical Station at the base of the upper section (as Fig. 1) as an and precipitation to analyze the influence of water conservancy example; the watershed above this site has an area of 2 928 km2 and hydropower projects on the magnitude and delivery of ru- that contains a river length of 153 km with a steep average noff in the Upper Qingjiang River Basin. slope of 6.5‰. Carbonate rocks underlie 56% of the upper basin which consequently has well developed karst features in- 1 STUDY AREA, DATA SOURCES AND METHODS cluding underground rivers and blind valleys (Chang et al., 1.1 Study Area 2012; Wang and Shen, 1995). Qingjiang River, located in the southwest part of Hubei The development of water resources and hydropower in Province, is the fourth largest tributary in the middle reaches of the Qingjiang River upstream of Enshi began with the 1964 the Yangtze River, contributing flows exceeded only by those construction of the Sanduxia Hydropower Station. Projects re- from Poyang Lake, Dongting Lake and the Han River. Qingjiang mained small until the medium-sized Chebahe Reservoir was River rises in Longdong Ravinel at the eastern foot of Qiyue- built in 1985. The combination of projects detailed in Table 1 shan in Lichuan City, Hubei Province. The river flows from has modified the response of the basin to rainfall. This paper analyzes the runoff changes before and after *Corresponding author: [email protected] the construction of the medium-sized Chebahe and Dalongtan © China University of Geosciences and Springer-Verlag Berlin reservoirs. The developments in the Upper Qingjiang River Ba- Heidelberg 2016 sin can be divided into a slow early stage (1960–1984) and a subsequent period of faster development that includes some Manuscript received October 1, 2014. larger projects (1985–2006; Table 1). Manuscript accepted December 23, 2014.

Sun, Y., Wan, J. W., Yang, S. Y., et al., 2016. Influences of Water Conservancy and Hydropower Projects on Runoff in Qingjiang River Upstream Basin. Journal of Earth Science, 27(1): 110–116. doi:10.1007/s12583-016-0640-5. http://en.earth-science.net Influences of Water Conservancy and Hydropower Projects on Runoff in Qingjiang River Upstream Basin 111

Table 1 Qingjiang River upstream water conservancy and hydropower projects statistics

Number Built Name Reservoir Hydropower station time Total capacity Surface area (m2) Type Size (104 m3) 1 1964 Sanduxia Hydropower Station 564 0.19×106 Storage plants Small

2 1971 Chebahe III Stage Hydropower Station -- -- Run-of river station plants Small

3 1976 Luojiatian Reservoir 114 0.15×106 -- --

4 1976 Huangnipo Reservoir 516 0.27×106 -- --

5 1982 Longwangtang Hydropower Station -- -- Storage plants Small

6 1984 Huajiaoba Reservoir 104 0.23×106 -- --

7 1985 Chebahe I Stage Hydropower Station 5 924 1.73×106 Storage plants Medium

8 1986 Chebahe II Stage Hydropower Station -- -- Run-of river station plants Small

9 1987 Dahepian Hydropower Station -- -- Run-of river station plants Small

10 1987 Xuezhaohe Hydropower Station -- -- Run-of river station plants Small

11 1993 Tianloudizhen Hydropower Station -- -- Run-of river station plants Medium

12 2001 Yunlonghe I Stage Hydropower Station -- -- Run-of river station plants Small

13 2006 Dalongtan Water Conservancy Hub Project 5 200 1.23×106 Storage plants Medium

108º38′ 109º32′ E

′ Xinbanqiao 30º33 N Surface stream Medium resevior Precipitation station Hydrologic station Longqiao River Small reservoir ChangpianDishuiyan River City

Daishui River

Yunlong River

Huishui River Qingjiang River Mazhe Dalongtan Resevior Qiyueshan Sanduxia Resevior Tuanbao Luojiaotian Resevior Qingjiang River Lichuan Huannipo Resevior Enshi Wangying ` Zhongxiao River Yasongxi River River Huajiaoba Resevior N Chebahe Resevior Chebahe River

SanbujieMaqian Jiantianba 0 7.2 km

′

30º09 Figure 1. The sketch map of the Qingjiang River Basin and location of rainfall and hydrological stations.

1.2 Data Sources and Methods rain storms were calculated by curve integration. The hydrologic data are from the Enshi Autonomous Pre- fecture Hydrographic and Water Resources Survey Bureau. 2 ANALYSIS OF CHARACTERISTICS OF RAINFALL Eleven rainfall stations record precipitation data and one hy- AND RUNOFF drological station measured runoff from 1960–2012 (Table 2). 2.1 Rainfall Daily precipitation amounts were summed to obtain monthly 2.1.1 Annual rainfall variations and annual values. The mean precipitation for the Upper Qing- The Upper Qingjiang River Basin is a steep area of karst jiang River Basin was derived using Theissen polygons (Lin et mountains and deep valleys, which for many years has had ab- al., 2003; Xu et al., 2001). Discharge at a given hydrological undant rainfall with an annual average rainfall of 1 470 mm. station is computed from measurements of velocity and depth Figure 2 shows that rainfall amounts in the upper basin tended at a cross section near the recorder. Trend lines (Li M X et al., to rise from the early 1960s through the 1980s, but this trend 2014; Li Z J et al., 2012; Xie et al., 2009; Hu et al., 2007; Wu, was punctuated by large fluctuations. Following a dip in the 1993; Ray et al., 1982) were used to quantify runoff and rain- early 1990’s, rainfall has fluctuated about a rather flat trend. fall tendencies from 1960 to 2012. The flood flows following

112 Yi Sun, Junwei Wan, Songyuan Yang, Xinghua Xue and Kun Huang

2.1.2 Monthly rainfall distribution 2.2 Long-Term Runoff Variations The rich basin rainfall is unevenly distributed over the Average flow of the Qingjiang River measured at the En- year, being heaviest in April to October. Precipitation during shi Hydroelectric Station from 1960–2012 (Fig. 2) is about 88.2 June and July generally exceeds 200 mm, with July typically m3/s, but exhibits large variations and a gentle decreasing trend. being the heaviest month. Winter rainfall amounts are lower, The 1960s featured sharp fluctuations ranging from 48.3 m3/s with January having the least at only 20–30 mm (Fig. 3). The in 1966 to 102.3 m3/s in 1967. Since 1983 the average flow at wettest six months from April to September account for about Enshi has tended to decline but inter-annual fluctuations have 76% of the total annual rainfall, while the dry season from Oc- remained large. Average flows at Enshi have decreased from tober to March receives the remaining 24% (Fig. 3). about 84.3 m3/s in 1990 to 71.3 m3/s in 2011. In short, Fig. 2 shows that both rainfall and runoff have tended to decrease over several decades in the Upper Qingjiang River Basin.

Table 2 Locations of rainfall and hydrological stations whose data records were analyzed in this study

Site name The time of construction Longitude (E) Latitude (N) Type Enshi 1933 109°29′ 30°18′ Rainfall and hydrological station Lichuan 1952 108°54′ 30°18′ Rainfall station Wangying 1956 108°42′ 30°16′ Rainfall station Xinbanqiao 1957 109°17′ 30°36′ Rainfall station Jiantianba 1957 109°10′ 30°10′ Rainfall station Xiliushui 1957 109°27′ 30°25′ Rainfall station Maqian 1962 108°49′ 30°11′ Rainfall station Tuanbao 1962 109°08′ 30°20′ Rainfall station Mazhe 1962 109°18′ 30°22′ Rainfall station Dishuiyan 1973 109°04′ 30°27′ Rainfall station Qiyueshan 1973 108°40′ 29°19′ Rainfall station

Precipitation 2 040 Nine-year moving average

1 700

1 360

Precipitation (mm) Precipitation

1 020

Enshi hydrologic station 120 Nine-year moving average

Flow (mFlow /s) 72

1960 1964 1968 1972 1976 1980 1984 1988 1992 1996 2000 2004 2008 2012 Time (year) Figure 2. The trend of annual runoff and rainfall from 1960 to 2012.

Influences of Water Conservancy and Hydropower Projects on Runoff in Qingjiang River Upstream Basin 113

200 3.2 Influence of Chebahe Reservoir on Storm Runoff 180 Two similar storm events, one before and one after con- 160 struction of the Chebahe reservoir, are compared to evaluate the effect of the project on river runoff (Table 3). Specifically, Fig. 140 5a shows the hydrograph response to the storm of September 120 15, 1983 that delivered 83.3 mm of rainfall, and Fig. 5b shows 100 the response to the storm of April 25, 1987 that delivered 109 mm of rain. Note that the total rainfall and the rainfall intensity 80 of the latter storm were highest. However, the flood peaks fol-

Precipitation (mm) Precipitation 60 lowing both storms feature a lag time of 9 h, while the peak 40 flow following the 1987 rainstorm was 1 470 m3/s lower than 8 3 20 the earlier event. Moreover, the total runoff of 1.24×10 m delivered by the 1987 rainstorm was significantly less than the 0 8 3 123456789101112 1.54×10 m delivered after the 1983 storm. These results Time (Mon.) document the beneficial effects of Chebahe Reservoir in re- taining flood water and reducing peak flows. Figure 3. 1960–2012 statistics of Qingjiang River upstream monthly rainfall. 3.3 Influence of the Dalongtan Project on Runoff

A pair of similar storm events was likewise selected to illu- 3 THE INFLUENCE OF WATER CONSERVANCY AND strate the effect of the Dalongtan Project on runoff delivery (Ta- HYDROPOWER PROJECTS ON RUNOFF ble 3). Figure 6a shows the discharge hydrograph following a 3.1 Long-Term Runoff Trends pre-reservoir rainstorm of May 29, 2004 rainstorm, while Fig. 6b From 1960–1984, the engineering projects on the Upper shows the response to a similar rainstorm of July 24, 2007 that Qingjiang River consisted of run-of-river hydroelectric stations postdated reservoir construction. Note that the total rainfall deli- and small reservoirs that had little or no storage capacity, and vered by these two rainstorms are very similar (Table 3), but that consequently had little long-term effect on runoff. However, the the average intensity of 4.5 mm/h for the earlier storm was lower period from 1985–2012 featured larger projects, particularly than the 5.6 mm/h for the later storm. Figure 6 shows that the construction of the two medium-sized reservoirs at Chebahe peak discharge following both rainstorms was about 1 650 m3/s, and Dalongtan, and streamflow subsequently decreased. Figure but that the lag time was only 6 h for the earlier event and 8 h for 4 provides regression lines relating runoff and rainfall for these the second. This example pair illustrates the beneficial effect of two periods. Note that the two regression lines are approx- the Dalongtan Project on flood peak delay. Moreover, Table 3 il- imately parallel, but that runoff before impoundment of the lustrates the total runoff of delivered by the first storm was great- Chebahe Reservoir had been systematically higher than it was er than that for the second, demonstrating effective floodwater afterward. A possible reason for this decline would be increased retention by Dalongtan Reservoir. evaporative losses due to the reservoir surfaces.

150 Before Chebahe Reservoir construction (1960-1984) 140 After Chebahe Reservoir construction (1985-2012) Fit curve of annual rainfall 130 Fit curve of annual rainfall

120

110 yx

3 =0.081 5 -35.427 R2=0.834 100

90 yx=0.079 2 -34.786 80 R2=0.828

Annual runoff (m runoff Annual /s)

40 1 000 1 100 1 200 1 300 1 400 1 500 1 600 1 700 1 800 1 900 2 000 2 100 Annual precipitation (mm) Figure 4. Annual runoff at Enshi, compared to annual rainfall in the 2 928 km2 catchment area.

114 Yi Sun, Junwei Wan, Songyuan Yang, Xinghua Xue and Kun Huang

Table 3 Four rainstorms analyzed in this study

Time Duration of Rainfall Rainfall intensity Peak discharge Integrated flow Remark rainfall (h) precipitation (mm) (mm/h) (m3/s) discharged (m3) Before the Chebahe Reservoir Sept. 15–16, 1983 17 83.6 4.91 1 700 1.54×108 construction After the Chebahe Reservoir Apr. 25–26, 1987 13 109 8.38 1 470 1.24×108 construction Before Dalongtan Water Conservancy May 29–30, 2004 18 80.9 4.49 1 650 1.12×108 Hub Project construction After Dalongtan Water Conservancy Jul. 24–25, 2007 14 78.2 5.59 1 650 1.00×108 Hub Project construction

1 800 0

1 600 (a) 1983 3

1 400 6 9 1 200 12 3 1 000 15 800 18

Flow (mFlow /s) 600 21

400 24 (mm/h) intensity Rainfall 200 27 0 30

830915 08:00 830915 12:00 830915 16:00 830915 20:00 830915 24:00 830916 04:00 830916 08:00 830916 12:00 830916 16:00 830916 20:00 830916 24:00 830917 04:00 830917 08:00 830917 12:00 830917 16:00 830917 20:00 830917 24:00 830918 04:00 830918 08:00 830918 12:00 830918 16:00 830918 20:00

1 800 0 (b) 1987 1 600 3

1 400 6 9 1 200 12 3 1 000 15 800 18

Flow (mFlow /s) 600 21

400 24 (mm/h) intensity Rainfall 200 27 0 30

870424 12:00 870424 16:00 870424 20:00 870424 24:00 870425 04:00 870425 08:00 870425 12:00 870425 16:00 870425 20:00 870425 24:00 870426 04:00 870426 08:00 870426 12:00 870426 16:00 870426 20:00 870426 24:00 870427 04:00 870427 08:00 870427 12:00 870427 16:00 870427 20:00 870427 24:00

Figure 5. The runoff response at Enshi to rainfall events before and after the 1985 construction of Chebahe reservoir, showing a decrease in peak flow for storms delivering similar amounts of total rain. (a) September 15, 1983; (b) April 25, 1987.

4 CONCLUSION losses from the reservoir surface. In addition, comparison of the Regression analysis of annual rainfall and runoff data from runoff responses to similar, individual storms before and after re- the Upper Qingjiang River Basin from 1960 to 2012 demonstrate servoir construction show significant stormwater retention by the a strong correlation with precipitation received, as well as a sig- reservoirs. Moreover, a beneficial reduction of peak flows is nificant, 13 m3/s reduction of average annual runoff following suggested for the Chebahe Reservoir, while an increase in the lag reservoir construction. This decrease may be due to evaporative time is suggested for the Dalongtan Reservoir.

Influences of Water Conservancy and Hydropower Projects on Runoff in Qingjiang River Upstream Basin 115

2 000 0 (a) 2004 2 1 800 4 1 600 6 1 400 8 1 200 10

3 1 000 12 14

Flow (mFlow /s) 800 16 600

18 Rainfall intensity (mm /h) 400 20 200 22 0 24

0529 08:00 0529 12:00 0529 16:00 0529 20:00 0529 00:00 0530 04:00 0530 08:00 0530 12:00 0530 16:00 0530 20:00 0530 00:00 0531 04:00 0531 08:00 0531 12:00 0531 16:00 0531 20:00 0531 00:00 0601 04:00

2 000 0 1 800 (b) 2007 2 4 1 600 6 1 400 8 1 200

3 10 1 000 12 800 14

Flow (mFlow /s) 600 16

400 18 Rainfall intensity (mm /h) 20 200 22 0 24

070723 04:00 070723 08:00 070723 12:00

070723 16:00 070723 20:00 070723 24:00 070724 04:00 070724 08:00 070724 12:00

070724 16:00 070724 20:00 070724 24:00 070725 04:00 070725 08:00 070725 12:00

070725 16:00 070725 20:00 070725 24:00 Figure 6. The runoff response at Enshi to storms before and after the 2006 construction of Dalongtan Reservoir, showing an increase in lag time.

ACKNOWLEDGMENTS sources, 34(6): 607–618 This study was supported by the National Natural Hasenmueller, E. A., Criss, R. E., 2013. Water Balance Esti- Science Foundation of China (No. 31460132) and the Scien- mates of Evapotranspiration Rates in Areas with Varying tific Research Project of Hubei Provincial Department of Land Use. In: Alexandris, S. G., ed., Evapotranspiration— Education (No. Q20122901). Comments from Prof. Robert E. An Overview. Intech. 1–21 Criss and Prof. Zhonghua Tang are gratefully acknowledged. Hu, X. L., Yang, S. P., Zhang, C. P., 2007. The Relationship The final publication is available at Springer via between Annual Rainfall and Surface Runoff in Yinghe http://dx.doi.org/10.1007/s12583-016-0640-5. Watershed in the Upstream of the Huaihe River Basin. Research of Soil and Water Conservation, 14(4): 20–23 REFERENCES CITED (in Chinese with English Abstract) Chang, H., Jin, W. Q., Wang, S. C., et al., 2012. Evolution Huang, Q., Jiang, X. H., Liu, J. P., et al., 2002. Study on the Process of the Downstream of Qingjiang River since Late Law of Annual Runoff Variation under the Duality Model Middle Pleistocene in Western Hubei Province. Geos- in Yellow River. Progress in Natural Science, 12(8): cience, 26(1): 99–106 (in Chinese with English Abstract) 874–877 (in Chinese with English Abstract) Crosbie, R. S., McCallum, J. L., Walker, G. R., et al., 2010. Mod- Ismaiylov, G. K., Fedorov, V. M., 2001. Analysis of elling Climate-Change Impacts on Groundwater Recharge in Long-Term Variations in the Volga Annual Runoff. Water the Murray-Darling Basin, Australia. Hydrogeology Journal, Resources, 28(5): 469–477 18(7): 1639–1656. doi:10.1007/s10040-010-0625-x Li, M. X., Lü, H. S., Zhang, S. L., et al., 2014. Application of Dobrovolski, S. G., 2007. The Issue of Global Warming and Annual Runoff Calculating Based on Budyko Hypothesis Changes in the Runoff of Russian Rivers. Water Re- in Simulated Annual Discharge of Humid Watershed.

116 Yi Sun, Junwei Wan, Songyuan Yang, Xinghua Xue and Kun Huang

Water Resources and Power, 32(4): 26–29 (in Chinese University (Natural Science Edition), 35(2): 153–159 (in with English Abstract) Chinese with English Abstract) Li, Z. J., Yu, S. S., Li, Q. L., et al., 2012. Regional Pattern of Wang, Z. Y., Shen, J. F., 1995. Karst Landscapes and Their Rainfall-Runoff Relationship. Journal of Hohai University Evolution in Reaches of the Qingjiang River, Western (Natural Sciences), 40(6): 597–604 (in Chinese with Eng- Hubei. Earth Science—Journal of China University of lish Abstract) Geosicences, 20(4): 439–444 (in Chinese with English Lin, K. P., Sun, C. Z., Zheng, F. Q., et al., 2003. Calculation Abstract) Method of Area Rainfall over Hilly Land and Its Applica- Wang, Z. Y., Wan, J. W., 1999. Qingjiang Basin Water-Eroded tion. Meteorological Monthly, 29(10): 8–12 (in Chinese Cave Development. China Karst, 18(2): 151–158 (in Chi- with English Abstract) nese with English Abstract) Ling, H. B., Xu, H. L., Fu, J. Y., 2014. Changes in Intra- Wu, J. C., 1993. Optimzing Research on the Statistic Correla- Annual Runoff and Its Response to Climate Change and tion in Hydrology. Journal of Wuhan University of Hy- Human Activities in the Headstream Areas of the Tarim draulic and Electric Engineering, 26(6): 675–678 (in River Basin, China. Quaternary International, 336(26): Chinese with English Abstract) 158–170. doi:10.1016/j.quaint.2013.08.003 Xie, P., Chen, G. C., Chen, L., 2009. Assessment of Water Re- Liu, H. Y., Li, Z., 2002. Hydrological Regime Changing sources Based on Rainfall-Runoff Relationship in Chang- Process and Analysis of Its Influencing Factors in a Typi- ing Environments. Resources Science, 31(1): 69–74 (in cal Wetland Watershed of the Sanjiang Plain. Journal of Chinese with English Abstract) Natural Resource, 20(4): 494–501 (in Chinese with Eng- Xu, J., Lin, J., Yao, X. X., et al., 2001. Calculating Method of lish Abstract) Area Rainfall over Seven River Valleys and Its Applica- Mileham, L., Taylor, G. R., Todd, M., et al., 2009. The Impact tion. Meteorological Monthly, 27(11): 13–16 (in Chinese of Climate Change on Groundwater Recharge and Runoff with English Abstract) in a Humid, Equatorial Catchment: Sensitivity of Projec- Xu, J. X., 2011. Variation in Annual Runoff of the Wudinghe tions to Rainfall Intensity. Hydrological Sciences Journal, River as Influenced by Climate Change and Human Activ- 54(4): 727–738 ity. Quaternary International, 244(2): 230–237. Pan, Z. T., Zhang, Y. J., Liu, X. D., et al., 2016. Current and Future doi:10.1016/j.quaint.2010.09.014 Precipitation Extremes over Mississippi and Yangtze River Zhang, S. Q., Xu, M., Xu, J. L., et al., 2013. Estimating the Basins as Simulated in CMIP5 Models. Journal of Earth Characteristics of Runoff Inflow into Lake Gojal in Un- Science, 27(1): 22–36. doi:10.1007/s12583-016-0627-2 gauged, Highly Glacierized Upper Hunza River Basin, Ray, K., 1982. Hydrology for engineers. In: Linsley, J., Max, Pakistan. Journal of Earth Science, 24(2): 234–243. A., eds., McGraw-Hill, New York. 120–140 doi:10.1007/s12583-013-0324-3 Ren, L. H., Zhang, W., Li, C. H., et al., 2001. Impacts of Hu- Zhang, Y., Wang, J., Jing, J., et al., 2014. Response of man Activities on River Runoff in North China. Journal of Groundwater to Climate Change under Extreme Climate Hehai University (Natural Sciences), 29(4): 13–18 (in Conditions in North China Plain. Journal of Earth Science, Chinese with English Abstract) 25(3): 612–618. doi:10.1007/s12583-014-0443-5 Shen, J. F., 1996. Qingjiang Basin Karst Research. Geological Zhou, Y. Y., Shi, C. X., Du, J., et al., 2012. Characteristics and Publishing Press, Beijing. 223 (in Chinese) Causes of Changes in Annual Runoff of the Wuding River Su, X. L., Kang, S. Z., X. M., et al., 2007. Impact of Climate in 1956–2009. Environmental Earth Sciences, 69(1): Change and Human Activity on the Runoff of Wei River 225–234. doi:10.1007/s12665-012-1949-8 Basin to the Yellow River. Journal of Northwest A & F