Hamid Yimit

Variations in groundwater levels and salinity in the Ili River Irrigation Area, Xinjiang, northwest China: a geostatistical approach

Groundwater levels and salinity are significant contributors to soil salinisation in irrigated areas. In this study, spatial and temporal variations of groundwater levels and salinity in the Ili River Irrigation Area in the western arid zone of China were analysed using a geostatistical approach. Results showed that: (1) groundwater salinity varied widely, with a maximum of 30.70 g/L and minimum of 0.20 g/L, while maximum groundwater level was 31.10 m and minimum was 0.54 m. The abundance of major ions in groundwater was in the order: Cl− > SO4 2– > Ca2+ > Mg2+ > K+ > Na+ > CO3 2– = HCO3 −. Groundwater salinity had a good positive correlation with EC, Cl−, Na+, HCO3 − and Mg2+ (correlation coefficient >0.90); (2) a Gaussian model was the most suitable semivariogram model to describe groundwater levels for four measurement periods, while a Spherical model was most suitable semivariogram model to describe groundwater salinity in March, September and November, and an Exponential model was most suitable variogram model for June. RA relatively strong spatial and temporal structure existed for groundwater levels and salinity due to very low nugget effects. The nugget-to-sill ratio indicated that groundwater levels and salinity in the study area have relatively strong spatial dependence. The groundwater levels and salinity showed an east–west, north–south U-shaped distribution in each measurement period; (3) maps of kriged groundwater levels and salinity showed that deeper groundwater was found in southern parts, with more shallow groundwater in northern parts of the study area. Higher groundwater salinity was found in central parts, with lower salinity in marginal parts of the study area. It is clear that substantial soil salinisation has taken place in central parts of the study area, and more attention should be paid to these areas to prevent future problems.

Oasis land-use change and its effects on the oasis eco-environment in Keriya Oasis, China

Land-use change in oases of arid zones play a significant role in the sustainable development and stability of oases. This paper presents a typical case of successful efforts to mitigate land-use change, its drivers and effects on the oasis eco-environment at Keriya Oasis in the western arid zone of China using remotely-sensed data, official statistics, and data collected by field investigation. Mathematical models were developed to quantify important elements related to land-use change, including net change and total change. The results indicate that: (1) approximately 17% of land-use types of Keriya Oasis changed between 1991 and 2002; (2) socioeconomic development, climate change, and economic polices contributed to land-use change in the oasis; (3) inappropriate human activities were the main cause of land-use change and eco-environmental degradation in the oasis; and (4) the stability of the oasis is threatened by land-use change and unexpected eco-environmental changes in the oasis and oasis–desert ecotone. The study suggests irrational human activity in arid zones, and that caution should be exercised to maintain stability and sustainable development of oases.

Variations in Ecosystem Service Value in Response to Oasis Land-use Change in Keriya Oasis, Tarim Basin, China

ABSTRACT: This study utilized satellite data and the published coefficients about the world and Chinas ecosystem to analyze the effects of oasis land-use change on ecosystem services in Keriya Oasis where both economic development and arid, fragile ecosystems have strongly affected land use. A sensitivity analysis was employed to determine the effect of manipulating these coefficients on the estimated values. Results indicated that: (1) the total values of ecosystem service in Keriya Oasis were about

Surface and Ground Water Quality in Eli River Valley, China

232.2 million.

A Simplified Model for Conjunctive Use of Water Resources for Control of Soil Salinization in Eli River Valley

212.8 million, and

The Variation in Water Quality of Urban River and its Driving Forces

207.2 million in 1991, 2002, and 2008, respectively, and the net decline in ecosystem service value was about

The landscape patterns change of Tarim Populus Nature Reserve and its eco-environmental effects, Xinjiang, China

25.0 million within 1991–2008; (2) the aggregated ecosystem service value of medium-cover grassland, wetland, low-cover grassland, cropland, and water body was about 90% of the total value; (3) waste treatment and soil formation were the top two ecological functions with high service value, and contributing about 41% of the total services value; and (4) ecosystem services values estimated in this study were inelastic with respect to the value coefficients. Therefore, the estimation was robust in spite of uncertainties on the value coefficients. A reasonable land-use plan should be based on rigorous environmental impact analyses for maintaining stability and sustainable development of Keriya Oasis.

The Impact of Precipitation and Temperature on Net Primary Productivity in Xinjiang, China from 1981 to 2000

Water is the major limiting factor in agriculture in arid and semi arid regions. The shortage of water resources of good quality is becoming an important issue. The main goal of this study is to analyze the quality of ground and surface water in Eli River Valley and analyze the feasibility of the use of ground and surface water for irrigation in the study area. On the basic of the monitored data of surface and ground water in Eli River Valley in August of 2008, the water quality were evaluated .The results showed that the mean anion concentrations occur in the order SO 4 2- > Cl - and cations in the order Ca 2+ >Na + > Mg 2+ > K + for groundwater while mean anion concentrations occur in the order SO 4 2+ > Cl - and cations in the order Na + > Ca 2+ > Mg 2+ > K + for surface water. The type of groundwater is moderately saline while the type of surface water is slightly saline. Both surface and ground water could be used for irrigation. In the study area, we can solve the problem of water shortage by conjunctive use of ground and surface water.

Groundwater Depth Variation And Its Effects On The Condition of Soil And Vegetation In Qira Oasis

Water is the major limiting factor in agriculture in arid and semi arid regions. Change in the hydrologic balance in irrigation areas has resulted in high water tables and salinization of soil. However, where suitable aquifers exist, groundwater pumping and irrigation application after mixing with fresh surface waters can control the secondary salinization of soil and water table depth and improve productivity of degraded land. In this study, the cause of soil salinization in Eli River Valley was analyzed by developing a simplified model for conjunctive use of surface water and groundwater. The model based on mass conservation of salt and water. It enables an estimate to be made of rootzone salinity for particular salinity level of groundwater being used in mixed with surface water. We found that the depth of groundwater recharge through leaching results in the secondary salinization of soil in irrigated area in arid zone, especially under saline groundwater conditions. The results of this study provide a scientific base for the improvement of water quality, sustainable water use and control of soil salinization in the study area.

Estimating crop water stress with ETM+ NIR and SWIR data

Urban river is an important component of urban ecosystem. With the rapid development of city economy, urbanization has resulted many problems of city eco-environment, especially deterioration of water quality. The main goal of this present study is to assess the impact of urban activities on river water quality for the study area. On the basic of the monitored data of Tuman River and statistics concerned with economic and social development of Tuman River basin, the water quality were evaluated. Five major pollutants were selected by factor analysis on 13 pollution indexes. Then the driving forces of the pollution of Tuman River were analyzed. The results showed that SS is the major pollutant in Tuman River. In arid zone, total suspended particulates have great influences on the water quality of urban river. Furthermore, industrialization, overpopulation and land use and land cover changes have influences on the water quality of urban river to certain extend, so human activities in arid zone should be cautious.