Subsurface stormflow is a dominant runoff mechanism in steep humid mountainous areas.An insite measurement of subsurface stormflow suggests that the bedrock surface plays an important role in the runoff generation and...Subsurface stormflow is a dominant runoff mechanism in steep humid mountainous areas.An insite measurement of subsurface stormflow suggests that the bedrock surface plays an important role in the runoff generation and routing process,which was rarely adopted in hydrological modelling studies.To improve the runoff simulation performance,the bedrock surface topographic index is introduced,and a modified TOPMODEL based on the bedrock surface topographic index is developed to simulate the runoff.The modified TOPMODEL is applied to the Huangbengliu(HBL),a steep watershed in Gongga Mountain,and proved to be more appropriate for the HBL watershed,especially for peak simulation.The Nash-Sutcliffe model efficiency(NSE)is improved from 0.24 to 0.58 in the calibration period and from 0.40 to 0.62 in the verification period.The result of this study can advance the understanding of the mechanism of flash floods and contribute flood control and disaster prevention in the HBL watershed and similar areas.展开更多
Background:Central Himalayan forested catchments provide fresh water supply and innumerable ecosystem services to millions of people.Hence,the understanding of linkages between forests and water is very crucial for av...Background:Central Himalayan forested catchments provide fresh water supply and innumerable ecosystem services to millions of people.Hence,the understanding of linkages between forests and water is very crucial for availability and quality of water at catchment scale.Therefore,the present study aims to understand the hydrological response of two forested catchments(namely,Arnigad and Bansigad)in the Central Himalayan Region.Methods:Threeyears’data(March,2008 to February,2011)were collected from meteorological and hydrological stations in Arnigad and Bansigad catchments.The present paper describes the mean hydrological response of these forested catchments investigated through detailed field investigation.Results:The annual hyetograph analysis revealed that the rainfall at both the catchments was highly seasonal,and wetperiod(June–September)plays a key role in catchment functioning.Exceedance of rainfall threshold of^200 mm(~10%of annual rainfall)significantly increased streamflow generation in both catchments.In Arnigad,the stream was perennial with a mean baseflow of^83mm per month(~6%of annual baseflow)whereas,Bansigad had greater seasonality due to lack of streamflow during the prewetperiod(March–May).Separation of hydrographs in Arnigad and Bansigad catchments i.e.stormflow(6%and 31%,respectively)and baseflow(50%and 32%,respectively)helped to understand the probability of flooding during wetperiod and drought during dryperiod.The forest ecosystem in Arnigad displayed healthier hydrological functioning in terms of reduced stormflow(82%),and enhanced baseflow(52%),soil moisture(13%),steady infiltration rate(22%)and lag time(~15 min)relative to Bansigad.These enhanced values indicated soil capability to store water in the forested catchment(Arnigad)and helped to understand the volume of water(discharge)that was available during dryperiod.The lower denudation rate at Arnigad by 41%resulted in decreased suspended sediment(18%)and bed load(75%)compared to Bansigad.Further,the enhanced dissolved solids in the Arnigad stream resulted from the higher organic matter generated in the forest floor.Conclusion:This study shows that rainfall during the wetperiod was the main driver of hydrological functioning,whereas,forests provided substantial services by regulating water balance,soil moisture and sediment budget through different mechanisms of forest components at catchmentscale in the Central Himalayan Region.展开更多
基金funded by the Major Program of National Natural Science Foundation of China(No.41790431)。
文摘Subsurface stormflow is a dominant runoff mechanism in steep humid mountainous areas.An insite measurement of subsurface stormflow suggests that the bedrock surface plays an important role in the runoff generation and routing process,which was rarely adopted in hydrological modelling studies.To improve the runoff simulation performance,the bedrock surface topographic index is introduced,and a modified TOPMODEL based on the bedrock surface topographic index is developed to simulate the runoff.The modified TOPMODEL is applied to the Huangbengliu(HBL),a steep watershed in Gongga Mountain,and proved to be more appropriate for the HBL watershed,especially for peak simulation.The Nash-Sutcliffe model efficiency(NSE)is improved from 0.24 to 0.58 in the calibration period and from 0.40 to 0.62 in the verification period.The result of this study can advance the understanding of the mechanism of flash floods and contribute flood control and disaster prevention in the HBL watershed and similar areas.
文摘Background:Central Himalayan forested catchments provide fresh water supply and innumerable ecosystem services to millions of people.Hence,the understanding of linkages between forests and water is very crucial for availability and quality of water at catchment scale.Therefore,the present study aims to understand the hydrological response of two forested catchments(namely,Arnigad and Bansigad)in the Central Himalayan Region.Methods:Threeyears’data(March,2008 to February,2011)were collected from meteorological and hydrological stations in Arnigad and Bansigad catchments.The present paper describes the mean hydrological response of these forested catchments investigated through detailed field investigation.Results:The annual hyetograph analysis revealed that the rainfall at both the catchments was highly seasonal,and wetperiod(June–September)plays a key role in catchment functioning.Exceedance of rainfall threshold of^200 mm(~10%of annual rainfall)significantly increased streamflow generation in both catchments.In Arnigad,the stream was perennial with a mean baseflow of^83mm per month(~6%of annual baseflow)whereas,Bansigad had greater seasonality due to lack of streamflow during the prewetperiod(March–May).Separation of hydrographs in Arnigad and Bansigad catchments i.e.stormflow(6%and 31%,respectively)and baseflow(50%and 32%,respectively)helped to understand the probability of flooding during wetperiod and drought during dryperiod.The forest ecosystem in Arnigad displayed healthier hydrological functioning in terms of reduced stormflow(82%),and enhanced baseflow(52%),soil moisture(13%),steady infiltration rate(22%)and lag time(~15 min)relative to Bansigad.These enhanced values indicated soil capability to store water in the forested catchment(Arnigad)and helped to understand the volume of water(discharge)that was available during dryperiod.The lower denudation rate at Arnigad by 41%resulted in decreased suspended sediment(18%)and bed load(75%)compared to Bansigad.Further,the enhanced dissolved solids in the Arnigad stream resulted from the higher organic matter generated in the forest floor.Conclusion:This study shows that rainfall during the wetperiod was the main driver of hydrological functioning,whereas,forests provided substantial services by regulating water balance,soil moisture and sediment budget through different mechanisms of forest components at catchmentscale in the Central Himalayan Region.
