Effects Of Climate Change And Human Activity Onstreamflow In The Headwater Region Of Beiluohe River Basin

The headwater region of Beiluohe river is a typical runoff yield under excess runoffgeneration. Both of precipitation and its intensity have a obvious influence on streamflow.Meanwhile, the precipitation in flood season accounts for a relatively high propertion, whichis benefit for the flood generation. Therefore, the different annual distribution of precipitationeasily lead to different annual streamflow under the condition of the same precipitation, whichcauses the appearance of abnormal meteorological and hydrological events and makesdifficulty of hydrological forecasting and the assessment on the effect of human activities onstreamflow. The energy industry, water conservancy and water and soil conservationmeasurement concentrates in the study area, so the water supply requires high guarantee rate.Therefore, it is a theoretical basis of integrity water resources management to evaluatewhether the annual distribution has an influence on abnormal meteorological and hydrologicalevents and quantitatively calculate the effect of climate change and human activities onstreamflow, which has a certain practical significance.Based on meteorological and hydrological data in terms of precipitation, temperature, airpressure, wind speed, relative humidity and sunshine hours, the period, trend, change pointand stage of the meteorological and hydrological data has been systematically analyzed bydifferent methods. According to abnormal meteorological and hydrological data in1988-1994,the annual distribution of precipitation is analyzed on whether it causes the appearance ofabnormal meteorological and hydrological events. The Zhanglu model has been developedtwice to make it used in the study area. The paper adopting the modified Zhanglu model, theeffect of climate change, including annual distribution of precipitation change, and humanactivities on streamflow has been quantitatively calculated. Then the reason of streamflowchange caused by human activities has been analyzed. The main results have been showed:1. The meteorological and hydrological data during1972-2008have been proved to havea approximate25years main period. The annual precipitation and the annual distribution ofprecipitation have no change. The annual mean temperature and streamflow respectivelysignificantly increase and decrease since1993and2002. Annual precipitation and annual streamflow respectively appear normal and wet, wet and normal during1988-1994and2000-2003, which reveals a different wet and drought type between annual precipitation andannual streamflow.2. The annual distribution of precipitation is an important reason of differentmeteorological and hydrological wet and drought types. Compared to1995-2000(the periodof different meteorological and hydrological wet and drought types), the month precipitationwet and drought events respectively have bigger and smaller intensity, period, which causesthe different types between meteorological and hydrological wet and drought events.3. It can be concluded that the main factor of runoff decreasing is human activity. On thebasis of regional applicability of Zhanglu model in the headwater region of Beiluohe river, theCvof annual distribution of precipitation has been added as a independent variable, whichmakes the Zhanglu model used in calculating the effect of climate change and humanactivities. The results have been showed as follows: the measured runoff depth decreases by10.27mm, the runoff depth decreases by0.61mm caused by comprehensive change ofmeteorological data in terms of increasing of precipitation (4.5mm), decreasing of the ETo(-6.1mm) and the Cvvalue (-0.01) and the runoff depth decreases by9.66mm caused byhuman activity.