The present study concerns the lowlands of the Birnin Lokoyo watershed located in the Matankari Rural Commune (Southwestern borders of the large Iullemmeden basin in the Niger). Dominated by the Birnin Lokoyo pond, th...The present study concerns the lowlands of the Birnin Lokoyo watershed located in the Matankari Rural Commune (Southwestern borders of the large Iullemmeden basin in the Niger). Dominated by the Birnin Lokoyo pond, this watershed faced with the continuous silting up of the minor bed, dissipates further upstream in the east, so that it moves downstream to the west for the benefit of the populations of Matankari city. The main objective of this work is to analyze the representative elements of the new climatic and environmental situation as well as the various factors determining the surface conditions in the watershed. The methodological approach is based on documentary research, field observations, individual surveys and interviews with targeted groups. The results show that the silting up of the lowlands is the result of the concomitant degradation of the plant cover and the soils, which, as a result, triggered the development of crusting surfaces and area erosion on the slopes. The study underlined the importance of endogenous knowledge in the choice of remedies against the silting up of lowlands. In addition, rational land management practices on plateaus and structures (within the watershed) do not seem to be in phase with topographical factors and the tectonic framework. This work is part of the vision of better management of glacis on the banks, but also of sills subject to regressive erosion upstream and in order to guide the policies of resilience of the populations.展开更多
Based on runoff, air temperature, and precipitation data from 1960 to 2010, the effects of climate change on water resources in the arid region of the northwestern China were investigated. The long-term trends of hydr...Based on runoff, air temperature, and precipitation data from 1960 to 2010, the effects of climate change on water resources in the arid region of the northwestern China were investigated. The long-term trends of hydroclimatic variables were studied by using both Mann-Kendall test and distributed-free cumulative sum （CUSUM） chart test. Results indicate that the mean annual air temperature increases significantly from 1960 to 2010. The annual precipitation exhibits an increasing trend, especially in the south slope of the Tianshan Mountains and the North Uygur Autonomous Region of Xinjiang in the study period. Step changes occur in 1988 in the mean annual air temperature time series and in 1991 in the precipitation time series. The runoff in different basins shows different trends, i.e., significantly increasing in the Kaidu River, the Aksu River and the Shule River, and decreasing in the Shiyang River. Correlation analy- sis reveals that the runoff in the North Xinjiang （i.e., the Weigan River, the Heihe River, and the Shiyang River） has a strong positive relationship with rainfall, while that in the south slope of the Tianshan Mountains, the middle section of the north slope of the Tianshan Mountains and the Shule River has a strong positive relationship with air temperature. The trends of rtmoff have strong negative correla- tions with glacier coverage and the proportion of glacier water in runoff. From the late 1980s, the climate has become warm and wet in the arid region of the northwestern China. The change in runoff is interacted with air temperature, precipitation and glacier coverage. The results show that streamflow in the arid region of the northwestern China is sensitive to climate change, which can be used as a reference for regional water resource assessment and management.展开更多
文摘The present study concerns the lowlands of the Birnin Lokoyo watershed located in the Matankari Rural Commune (Southwestern borders of the large Iullemmeden basin in the Niger). Dominated by the Birnin Lokoyo pond, this watershed faced with the continuous silting up of the minor bed, dissipates further upstream in the east, so that it moves downstream to the west for the benefit of the populations of Matankari city. The main objective of this work is to analyze the representative elements of the new climatic and environmental situation as well as the various factors determining the surface conditions in the watershed. The methodological approach is based on documentary research, field observations, individual surveys and interviews with targeted groups. The results show that the silting up of the lowlands is the result of the concomitant degradation of the plant cover and the soils, which, as a result, triggered the development of crusting surfaces and area erosion on the slopes. The study underlined the importance of endogenous knowledge in the choice of remedies against the silting up of lowlands. In addition, rational land management practices on plateaus and structures (within the watershed) do not seem to be in phase with topographical factors and the tectonic framework. This work is part of the vision of better management of glacis on the banks, but also of sills subject to regressive erosion upstream and in order to guide the policies of resilience of the populations.
基金Under the auspices of Major State Basic Research Development Program of China(No.2010CB951003)the National Climate Central,China Meteorological Administration,for providing the meteorological data for this study
文摘Based on runoff, air temperature, and precipitation data from 1960 to 2010, the effects of climate change on water resources in the arid region of the northwestern China were investigated. The long-term trends of hydroclimatic variables were studied by using both Mann-Kendall test and distributed-free cumulative sum （CUSUM） chart test. Results indicate that the mean annual air temperature increases significantly from 1960 to 2010. The annual precipitation exhibits an increasing trend, especially in the south slope of the Tianshan Mountains and the North Uygur Autonomous Region of Xinjiang in the study period. Step changes occur in 1988 in the mean annual air temperature time series and in 1991 in the precipitation time series. The runoff in different basins shows different trends, i.e., significantly increasing in the Kaidu River, the Aksu River and the Shule River, and decreasing in the Shiyang River. Correlation analy- sis reveals that the runoff in the North Xinjiang （i.e., the Weigan River, the Heihe River, and the Shiyang River） has a strong positive relationship with rainfall, while that in the south slope of the Tianshan Mountains, the middle section of the north slope of the Tianshan Mountains and the Shule River has a strong positive relationship with air temperature. The trends of rtmoff have strong negative correla- tions with glacier coverage and the proportion of glacier water in runoff. From the late 1980s, the climate has become warm and wet in the arid region of the northwestern China. The change in runoff is interacted with air temperature, precipitation and glacier coverage. The results show that streamflow in the arid region of the northwestern China is sensitive to climate change, which can be used as a reference for regional water resource assessment and management.
