Application assessment of GRACE and CHIRPS data in the Google Earth Engine to investigate their relation with groundwater resource changes(Northwestern region of Iran)          下载免费PDF全文

Mehdi Afraz  Mobin Eftekhari  Mohammad Akbari  Elyasi Ali Haji  Zahra Noghani 《地下水科学与工程》2021,9(2):102-113

In recent years, drought has become a global issue, especially in arid and semi-arid areas. It is without doubt that the identification and monitoring of the drought phenomenon can help to reduce the damages that would occur. In addition, rain is one of the factors which directly affect the water levels of underground water reservoirs. This research applied a linear gradient regression method developed on the basis of GRACE, CHIRPS, and data from monitoring wells to investigate the groundwater storage changes.These data have been analyzed on the Google Earth Engine platform. In order to conduct temporal and spatial analyses, the water levels of the aquifer were generated from the monitoring wells and zoned into five classes. Also, the amount of water storage and rain from the year 2003 to 2017 in the West Azerbaijan Province were investigated using the GRACE satellite and the CHIRPS data, respectively. The results obtained from the GRACE satellite data show that the average water level in the underground reservoirs in Iran had started to decrease since 2008 and reached its peak in 2016 with an average decrease of 16 cm in that year. The average annual decline of groundwater level in the studied time period was 5 cm. A chart developed from the CHIRPS annual rainfall data indicates that the biggest decline in rainfall occurred in 2008, and the declining trend has remained steady. Linear analyses were made on GRACE with CHIRPS results and monitoring wells data separately, from which the correlation coefficients are between 86% and 97%, showing generally high correlations. Furthermore, the results obtained from the zoning of the aquifer showed that in the period of 2004 to 2016, due to the decrease in rainfall and the excessive withdrawal of groundwater, the water levels also decreased.  相似文献   

Spatial distribution and temporal trends of rainfall and erosivity in the Eastern Africa region   总被引：1，自引：0，他引：1       下载免费PDF全文

Ayele Almaw Fenta  Hiroshi Yasuda  Katsuyuki Shimizu  Nigussie Haregeweyn  Takayuki Kawai  Dagnenet Sultan  Kindiye Ebabu  Ashebir Sewale Belay 《水文研究》2017,31(25):4555-4567

Soil erosion by water is one of the main environmental concerns in the drought‐prone Eastern Africa region. Understanding factors such as rainfall and erosivity is therefore of utmost importance for soil erosion risk assessment and soil and water conservation planning. In this study, we evaluated the spatial distribution and temporal trends of rainfall and erosivity for the Eastern Africa region during the period 1981–2016. The precipitation concentration index, seasonality index, and modified Fournier index have been analysed using 5 × 5‐km resolution multisource rainfall product (Climate Hazards Group InfraRed Precipitation with Stations). The mean annual rainfall of the region was 810 mm ranging from less than 300 mm in the lowland areas to over 1,200 mm in the highlands being influenced by orography of the Eastern Africa region. The precipitation concentration index and seasonality index revealed a spatial pattern of rainfall seasonality dependent on latitude, with a more pronounced seasonality as we go far from the equator. The modified Fournier index showed high spatial variability with about 55% of the region subject to high to very high rainfall erosivity. The mean annual R‐factor in the study region was calculated at 3,246 ± 1,895 MJ mm ha^?1 h^?1 yr^?1, implying a potentially high water erosion risk in the region. Moreover, both increasing and decreasing trends of annual rainfall and erosivity were observed but spatial variability of these trends was high. This study offers useful information for better soil erosion prediction as well as can support policy development to achieve sustainable regional environmental planning and management of soil and water resources.  相似文献