Research on the Process of Runoff and Sediment-production in the Shunjiagou Small Watershed by Applying Automatic Measurement System

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1 Research on the Process of Runoff and -producton n the Shunjagou Small Watershed by Applyng Automatc Measurement System Zhou Janghong, Le Tngwu College of Hydraulc and Cvl Engneerng, Chna Agrcultural Unversty, Bejng 183, Chna E-mal: hljsbczjh@126.com Abstract: Based on the constructon of sol eroson synthess preventon and control plot project n the Northeast Black Earth Area, selectng representatve Shunjagou Small Watershed n Zhalantun,Inner Mongola as study case, the research focuses on runoff and sedment-producton by applyng automatc measurement system. The result ndcates that sedment concentraton has certan correlaton wth runoff and runoff amount can be used to estmate sedment concentraton when nformaton s ncomplete; the longer accumulated ranfall duraton and the larger ranfall amount, the closer the correlaton of the runoff amount and sedment concentraton. It s the frst tme to apply automatc measurement system n ths knd of research practce, and t breaks through the tradtonal method of determnaton runoff and sedment concentraton and realzes automatc data acquston at home and abroad. [The Journal of Amercan Scence. 26;2(4):12-17]. Key words: automatc measurement system; runoff; sedment concentraton 1. Introducton 2. Montorng method The Northeast Black Earth Area n Chna s one of three bg black earth areas n the world and mportant marketable gran base n Chna, manly dstrbutng at the aggradaton rollng platform of Xaoxng an Ra. and western sde of Changba Mt. n Chna Northeast Area. In the recent years Chna strengthened ncreasngly the control for sol eroson n the Northeast Black Earth Area and started a three-year sol eroson synthess preventon and control plot project n the Northeast Black Earth Area. Whle constructng plot project, sol and water conservaton montorng was carred out. The montorng has been carryng out for 2 years. The paper selects representatve Shunjagou Small Watershed n Zhalantun. Inner Mongola as study case. The small watershed s located n Shunjagou, Wuy Vllage, Gaotaz Town, Zhalantun Muncpalty and temperate contnental monsoon regon wth 4 mm-5 mm ranfall. The area has a typcal low mountan, hll landscape and black earth for ts sol type. The total area of the watershed s 5.85 km 2, sol eroson area s 3.1 km 2 and sol eroson modulus s t/km 2 /a. Sol eroson type appears water eroson and t manly forms surface eroson and gully on the slope surface of cultvated land. The research apples automatc measurement system to montor the varaton of runoff and sedment concentraton on-lne, then analyss the correlaton of the runoff amount and sedment producton. It wll provde sound foundaton for further research of sol eroson law n the area. 2.1 Montorng Equpment The montorng system s conssts of four parts, that s remote center control room, runoff wer, recevng computer room and automatc montorng devce. Remote center control room: The computer n the room can montor runoff and sedment concentraton at the wer on-lne, ndcate dynamc varaton of montored parameters and load down the data. And network transportaton and remote control are realzed. Recevng computer room: It s a 1 m 2 house made of brck, 6m away from runoff wer. The house s desgned satsfyng flood control requrement and easy for recevng and protecton. Runoff wer: It s V-notch wer wth 41 m wde, 1.6m hgh. Controlled area s 3.15 km 2, desgned maxmum dscharge 8.6 m 3 /s and 1 n 2 years flood. automatc montorng devce: A set of runoff and sedment concentraton automatc montorng devce, developed by Sol and Water Conservaton Research Insttute of Chna Scence Academy and Chna Agrculture Unversty, s appled n the research. It s manly conssts of one master control computer, a set of solar energy supply, a set of multple pont, needle water-level gage, one ray sedment concentraton sensng devce, a set of software for loadng data n the center computer, a devce of GSM remote data transportaton and a set of control and management software for montorng center. 12

2 2.2 Montorng Procedure 1) When ranfall forms runoff, flows through the wer and water level reaches certan heght, the system wll start automatcally. 2) A sedment concentraton devce s put nto the depth where survey s desgned to carry out at the wer; four ray sedment concentraton sensng devces are put n the runoff cross vertcally to montor gradent varaton of sedment concentraton at the runoff cross. Runoff and sedment concentraton can be calculated by usng the montored data from sedment concentraton devce and wer. When sensng devce starts workng, system wll survey, collect and memory the sensng data. 3) The master control computer controls and manages each sensng devce and gets montored sedment concentraton and runoff through workng management and data memory software. A set of data, that s sedment concentraton, water level and correspondng tme, s memorzed n the master control computer. 4) The data are loaddowned through RS232 nterface tmely, otherwse the data may be overlapped by new data or loss due to system falure. The data can also be transported to montorng center by means of GSM remote data transportaton net, conductng real-tme operaton, load downng data, lookng up data, analyzng data and prntng data. Automatc montorng s realzed. 3. Fndngs and Analyss The paper takes hydrologc data at Zhalantun Montorng Staton, Inner Mongola as study case, analyss the correlaton runoff and sedment concentraton n the watershed n order to provde a research base for further study. 3.1 Correlaton of Runoff and Concentraton concentraton G s an mportant parameter to ndcate sedment producton n a watershed. Under certan condton, the greater sedment dscharge, the hgher sedment producton. In the paper G can be expressed as G=q c (1) n whch q=runoff (m 3 /s); c=sedment dscharge (kg/m 3 ) Fgure 1, Fgure 2 and Fgure 3 are lnear relaton fgures of runoff and sedment concentraton on 19,2 and 21 June at Zhalantun Montorng Staton. The fgures show that runoff and sedment concentraton have good relatvty and Table 1 ndcates that the correlaton coeffcent at each montorng staton reaches.83. All facts demonstrate that there s a correspondng relaton between Runoff amount and sedment concentraton, sedment concentraton ncreases wth the runoff ncrease, namely water flow capacty for carryng sol ncreases wth the runoff ncrease. The relaton dffers at dfferent tme. Maybe the dfference s caused by ranfall ntensty, ranfall duraton and other factors y = x R 2 = Fgure 1. Runoff Amount and Concentraton Relatons at Zhalantun Hydrologc Staton July 19 13

3 y = 8.864x R 2 = Fgure 2. Runoff Amount and Concentraton Relatons at Zhalantun Hydrologc Staton on July 2 Concentraton(kg/s) y = x R 2 = Fgure 3. Runoff Amount and Concentraton Relatons at Zhalantun Hydrologc Staton on July 21 Table 1. Runoff amount and sedment concentraton fttng equaton and correlaton coeffcent Staton fttng equaton R 2 correlaton coeffcent R Zhalantun June 19 Y= Zhalantun June 2 Y= Zhalantun June 21 Y= Relaton of Concentraton and Runoff Fgure 4, Fgure 5 and Fgure 6 show the varaton of sedment concentraton and runoff. The fgures ndcate that the varaton of sedment concentraton s bascally same as the varaton of runoff. From the fgures we can fnd that the varaton of sedment concentraton and runoff s dvded nto two perods, namely rsng segment and fallng segment. Wth the ncrease of ranfall duraton, runoff and sedment all clmb up and reach ther peak, then turn to ther fallng segment. 14

4 :24: 21:36: 22:48: :: Fgure 4. Runoff Amount and Concentraton Change Curve at Zhalantun Hydrologc Staton on July :: 19:12: 2:24: 21:36: 22:48: Fgure 5. Runoff Amount and Concentraton Change Curve at Zhalantun Hydrologc Staton on July :: 1:12: 2:24: 3:36: 4:48: 6:: 7:12: 8:24: Fgure 6. Runoff Amount and Concentraton Change Curve at Zhalantun Hydrologc Staton on July

5 3.3 Calculaton of Cumulatve Ranfall and Cumulatve Dscharge When hydrologc data are complete we can calculate cumulatve runoff and cumulatve sedment dscharge for one tme ranfall. It compares wth cumulatve ranfall and gets ther relaton. Cumulatve runoff can be expressed as t Q = qdt q t n = (2) n whch Q=cumulatve runoff of certan perod (m 3 ); t=tme runoff flowng whole watershed(s); t=nterval of survey(s);q =runoff at certan survey tme(m 3 /s); =,1, 2 n Survey number of calculated perod. Based on formula(1), Cumulatve sedment dscharge s expressed correspondngly as G t n = t qcdt t = c q = = n g t (3) n whch G =cumulatve sedment dscharge of certan perod(kg); t g =sedment dscharge of certan survey perod(kg/s ); c =sedment concentraton of certan survey perod(kg/m 3 ) 4. Conclusons 1) It s the frst tme to apply automatc measurement system n ths knd of research practce, and t breaks through the tradtonal method of determnaton runoff and sedment concentraton and realzes automatc data acquston by computer, on-lne, real-tme and automatc measurement.the method reaches good results. 2) There s certan relatvty of sedment dscharge and runoff. It ndcates that runoff can be used to estmate sedment dscharge when the data are not complete, and the longer the cumulatve ranfall duraton and the greater cumulatve runoff, the closer the relaton of sedment dscharge and runoff. From the varaton of runoff and sedment concentraton, ther varatons are bascally same. They ncrease wth ranfall duraton and when reach ther peaks, begn to decrease. The varaton presents drectly two perods, namely rsng and fallng segment. 3) Calculaton methods for cumulatve runoff and cumulatve sedment dscharge are put forward. Ther relatvty wth cumulatve ranfall and sedment-producton laws for dfferent regons and dfferent ranfall wll be consdered n further research. Quotent of cumulatve sedment dscharge and cumulatve runoff can be calculated to demonstrate the character of underlyng surface. 4) Ranfall data collaton correspondng the sedment concentraton montorng should be strengthened n future montorng n order to set up relaton of ranfall, dscharge and sedment dscharge. Correspondence to: Le Tngwu Chna Agrcultural Unversty 151# E-mal: ddragon@publc3.bta.net.cn Zhou Janghong No.4 Wenzhong Street Nan gang Dstrct Harbn, Helongjang 151, Chna E-mal: hljsbczjh@126.com Author : Zhou Janghong, Female, born n 1968, Ph.D.,manly Engaged n the reseach of sol eroson process and mechansm, E-mal: hljsbczjh@126.com Receved: 8/28/26 References 1. Le Tngwu, Wang Hu, Zhao Jun, Lu Qngkun, Xa Weheng. Automatc system for dynamcal determnaton of sedment concentraton and flow rate n runoff. [J]. Transactons of the CSAE, 22, 18(5): Zhen Fenl. Dscuson on the Research Felds n Sol Eroson Study Whch Should be Stretched Urgently n Chna. Research of Sol and Water Conservaton,1999,6(2): Fan Yanzhun, Zhang Hongme, Cheng Yng. New Development on Concentraton Measurement. Bulletn of Wuhan Hyraulc and hydropower Unversty,1999,32(3): Lu Junhua, Intellgect Sensng System. : Publshng House of X an Electronc Scence and Technology Unversty, Fu Suhua, Fu Jnsheng, Wan Xaolan. Measurng Method Study on the Concentraton of Collector n runoff Small Area. Bulletn of Sol and Water Conservaton,23,6: Ye Zhhan,Lu Baoyuan,Lu Bngjun. Study and Experment on Sampler of Concentraton Collector n Small Runoff Area. Research,25,3: Mu Xngmn, Wang Fe, L Jng. New Development of Assessment Method on the Impact of Sol and Water Conservaton Measures on Rver Runoff. Bulletn of Sol and Water Conservaton,24,3: Gao Pelng, Le Tngwu, Zhao Jun. Method 16

6 Research and Forecastng on Runoff Concentraton of Slope Eroson. Research,24,5: Fan Yanzhun, Zhang Hongme, Cheng Yng. New Development on Concentraton Measurement. Bulletn of Wuhan Hyraulc and hydropower Unversty,1999,3: Gao Pelng, Le Tngwu, Shao Mng an. Experment and Research on Automatc Measurement System of Runoff and Sol Eroson n Small Watershed. Journal of Agrcultural Engneerng,25,1: