scholarly journals Downstream ecosystem responses to middle reach regulation of river discharge in the Heihe River Basin, China

2016 ◽  
Author(s):  
Y. Zhao ◽  
Y. P. Wei ◽  
S. B. Li ◽  
B. F. Wu
Keyword(s):  
River Discharge ◽  
Agricultural Development ◽  
River Regulation ◽  
Water Diversion ◽  
Heihe River ◽  
Catchment Management ◽  
Linear Regression Models ◽  
Landsat Images ◽  
Ecosystem Responses ◽  
Temperature And Precipitation

Abstract. Understanding the oasis ecosystem responses to upstream regulation is a challenge for catchment management for ecological restoration. This empirical study aimed to understand how oasis ecosystems including water, natural vegetation and cultivated land responded to the implementation of the Ecological Water Diversion Project (EWDP) in the Heihe River in China. The annual Landsat images from 1987 to 2015 were firstly used to characterize the spatial extent, frequency index and fractional coverage (for vegetation only) of these three oasis ecosystems and their relationships with hydrological (river discharge) and climatic variables (regional temperature and precipitation) were explored with linear regression models. The results show that river regulation of the middle reaches identified by the discharge allocation to the downstream basin experiences three stages, namely decreasing inflow (1987–1999), increasing inflow (2000–2007) and relative stable inflow (2008–2015). Both the current and previous years' combined inflow determines the surface area of the terminal lake (R2 = 0.841). Temperature has the most significant role in determining broad vegetation distribution, whereas hydrological variables had a significant effect only in near-river-channel regions. Agricultural development since the execution of the EWDP might have curtailed further vegetation recovery. These findings are important for the catchment managers' decisions about future water allocation plans.

scholarly journals Downstream ecosystem responses to middle reach regulation of river discharge in the Heihe River Basin, China

2016 ◽  
Vol 20 (11) ◽  
pp. 4469-4481 ◽  
Author(s):  
Yan Zhao ◽  
Yongping Wei ◽  
Shoubo Li ◽  
Bingfang Wu
Keyword(s):  
River Discharge ◽  
Agricultural Development ◽  
River Regulation ◽  
Water Diversion ◽  
Heihe River ◽  
Catchment Management ◽  
Linear Regression Models ◽  
Landsat Images ◽  
Ecosystem Responses ◽  
Temperature And Precipitation

Abstract. Understanding the oasis ecosystem responses to upstream regulation is a challenge for catchment management in the context of ecological restoration. This empirical study aimed to understand how oasis ecosystems, including water, natural vegetation and cultivated land, responded to the implementation of the Ecological Water Diversion Project (EWDP) in the Heihe River in China. The annual Landsat images from 1987 to 2015 were firstly used to characterize the spatial extent, frequency index and fractional coverage (for vegetation only) of these three oasis ecosystems and their relationships with hydrological (river discharge) and climatic variables (regional temperature and precipitation) were explored with linear regression models. The results show that river regulation of the middle reaches identified by the discharge allocation to the downstream basin experiences three stages, namely decreasing inflow (1987–1999), increasing inflow (2000–2007) and relative stable inflow (2008–2015). Both the current and previous years' combined inflow determines the surface area of the terminal lake (R2  =  0.841). Temperature has the most significant role in determining broad vegetation distribution, whereas hydrological variables had a significant effect only in near-river-channel regions. Agricultural development since the execution of the EWDP might have curtailed further vegetation recovery. These findings are important for the catchment managers' decisions about future water allocation plans.

scholarly journals Estimating Dynamics of Terminal Lakes in the Second Largest Endorheic River Basin of Northwestern China from 2000 to 2017 with Landsat Imagery

2019 ◽  
Vol 11 (10) ◽  
pp. 1164
Author(s):  
Bei Li ◽  
Yi-Chi Zhang ◽  
Ping Wang ◽  
Chao-Yang Du ◽  
Jing-Jie Yu
Keyword(s):  
River Basin ◽  
Water Consumption ◽  
Landsat Imagery ◽  
Water Diversion ◽  
Heihe River ◽  
Arid Environments ◽  
Lake Area ◽  
Landsat Images ◽  
East River ◽  
Terminal Lakes

Quantifying terminal-lake dynamics is crucial for understanding water-ecosystem-economy relationship across endorheic river basins in arid environments. In this study, the spatio-temporal variations in terminal lakes of the lower Heihe River Basin were investigated for the first time since the Ecological Water Diversion Project commenced in 2000. The lake area and corresponding water consumption were determined with 248 Landsat images. Vital recovery of lakes occurred two years after the implementation of the project, and the total lake area increased by 382.6%, from 30.7 to 148.2 km2, during 2002–2017. East Juyan Lake (EJL) was first restored as a project target and subsequently reached a maximum area of 70.1 km2. Water dispersion was initiated in 2003, with the East river prioritized for restoration. Swan Lake in the East river enlarged to 67.7 km2 by 2017, while the other four lakes temporarily existed or maintained an area < 7 km2, such as West Juyan Lake. Water consumed by lakes increased synchronously with lake area. The average water consumption of the six lakes was 1.03 × 108 m3/year, with 63% from EJL. The increasing terminal lakes; however, highlight the seasonal competition for water use between riparian vegetation and lake ecosystems in water-limited areas.

scholarly journals Simulation of river discharge in ungauged catchments by forcing GLDAS products to a hydrological model (a case study: Polroud basin, Iran)

2019 ◽  
Vol 20 (1) ◽  
pp. 277-286
Author(s):  
Hadis Pakdel Khasmakhi ◽  
Majid Vazifedoust ◽  
Safar Marofi ◽  
Abdollah Taheri Tizro
Keyword(s):  
River Discharge ◽  
Good Alternative ◽  
Observation Data ◽  
Ungauged Catchments ◽  
Discharge Data ◽  
The North ◽  
Temperature And Precipitation ◽  
North Of Iran ◽  
Land Data Assimilation ◽  
Land Data Assimilation System

Abstract Due to unavailability of sufficient discharge data for many rivers, an appropriate approach is required to provide accurate data for estimating discharge in ungauged watersheds. In this study, Global Land Data Assimilation System (GLDAS) datasets were integrated with Hydrologic Engineering Center Hydrologic Modeling System (HEC-HMS) to simulate the outlet river discharge in Polroud watershed, located in the North of Iran. Temperature and precipitation products generated by GLDAS were calibrated using regression analysis based on observation data for the period of 2004–2006. Then, river discharge was simulated by using HEC-HMS based on two different datasets (GLDAS meteorological product and gauged data) on the scale of the basin for the same period. The results clearly indicated that the forcing of GLDAS data into HEC-HMS model leads to promising results with acceptable correlation with observed data. Although, in comparison with direct GLDAS runoff products, the proposed approach improved the accuracy of river discharge, the problem of underestimation still reduces the expected accuracy. Because of global accessibility, GLDAS datasets would be a good alternative in ungauged or poorly gauged watersheds.

Post-Evaluation of the Ecological and Environmental Impact of Water Diversion Project in the Low Reaches of Heihe River

2012 ◽  
Vol 518-523 ◽  
pp. 1188-1191
Author(s):  
Gui Zhi Wang ◽  
De Shan Tang
Keyword(s):  
Environmental Impact ◽  
Local Environment ◽  
Water Diversion ◽  
Ecological Effect ◽  
Heihe River ◽  
Post Evaluation ◽  
Water Diversion Project ◽  
Ecology And Environment ◽  
Oasis Area ◽  
The Impact

Since 2001, Heihe River began to carry out the project of water transforming, which caused certain effect in the ecology and environment of the whole basin. Analyzing the change of climate, the ground water, the typical plant growth and the oasis area in nearly 10 years, master the impact of water diversion to the downstream ecology and environment. It shows that the implement of the project of water transforming has decreased the desertification area, expanded the oasis area and kept down the trend of decline of a water table, the populus diversifolia and other vegetation began to recover and grow. The water diversion of Heihe River acquired preferably ecological effect; the local environment has made great improvement.

scholarly journals Potential climate change impacts on temperate forest ecosystem processes

2013 ◽  
Vol 43 (10) ◽  
pp. 939-950 ◽  
Author(s):  
Emily B. Peters ◽  
Kirk R. Wythers ◽  
Shuxia Zhang ◽  
John B. Bradford ◽  
Peter B. Reich
Keyword(s):  
Great Lakes ◽  
Forest Type ◽  
Climate Change Impacts ◽  
Ecosystem Model ◽  
Climate Projections ◽  
Net N Mineralization ◽  
Long Term Effects ◽  
Ecosystem Responses ◽  
Temperature And Precipitation

Large changes in atmospheric CO2, temperature, and precipitation are predicted by 2100, yet the long-term consequences for carbon (C), water, and nitrogen (N) cycling in forests are poorly understood. We applied the PnET-CN ecosystem model to compare the long-term effects of changing climate and atmospheric CO2 on productivity, evapotranspiration, runoff, and net nitrogen mineralization in current Great Lakes forest types. We used two statistically downscaled climate projections, PCM B1 (warmer and wetter) and GFDL A1FI (hotter and drier), to represent two potential future climate and atmospheric CO2 scenarios. To separate the effects of climate and CO2, we ran PnET-CN including and excluding the CO2 routine. Our results suggest that, with rising CO2 and without changes in forest type, average regional productivity could increase from 67% to 142%, changes in evapotranspiration could range from –3% to +6%, runoff could increase from 2% to 22%, and net N mineralization could increase 10% to 12%. Ecosystem responses varied geographically and by forest type. Increased productivity was almost entirely driven by CO2 fertilization effects, rather than by temperature or precipitation (model runs holding CO2 constant showed stable or declining productivity). The relative importance of edaphic and climatic spatial drivers of productivity varied over time, suggesting that productivity in Great Lakes forests may switch from being temperature- to water-limited by the end of the century.

scholarly journals Climate change impacts on agriculture sector: A case study of Pakistan

2021 ◽  
Vol 51 (8) ◽  
Author(s):  
Uzair Ali ◽  
Wang Jing ◽  
Jialin Zhu ◽  
Zhibek Omarkhanova ◽  
Shah Fahad ◽  
...  
Keyword(s):  
Climate Change ◽  
Agricultural Production ◽  
Crop Production ◽  
Agricultural Development ◽  
Negative Impact ◽  
Influence Factors ◽  
Climate Change Impacts ◽  
Agriculture Sector ◽  
Temperature And Precipitation ◽  
Vulnerability To Climate Change

ABSTRACT: The current article looks at the effects of climate change on agriculture, especially crop production, and influence factors of agricultural development in terms of their rational use in Pakistan. Due to the dependence of economic development, and agriculture in the South Asian region on access to renewable national resources and the associated vulnerability to climate change, the limited financial and professional resources of the Islamic Republic of Pakistan require a clear definition of national priorities in this area. In the preparation of this article, general scientific cognition methods, in particular, empirical-theoretical methods were used. Grouping and classification methods have been used to process and systematize the data. The ability to change productivity, depending on the variation of the average annual air temperature and the average annual precipitation rate, was considered using a two-factor regression model. The main finding of the study is that temperature and precipitation have a negative impact on agricultural production. This study can provide a scientific justification for the specialization of agricultural production in the regions of Pakistan as well as the execution of the necessary agricultural activities.

scholarly journals Modelling and Forecasting of Ikpoba River Discharge in the Niger Delta Region using Adaptive Neuro-Fuzzy Inference System (ANFIS)

2020 ◽  
Vol 4 (2) ◽  
pp. 432-449
Author(s):  
S. Egbiki ◽  
J. O. Ehiorobo ◽  
O. C. Izinyon
Keyword(s):  
Climate Change ◽  
Fuzzy Inference System ◽  
River Discharge ◽  
Fuzzy Inference ◽  
Inference System ◽  
Discharge Data ◽  
Acceptable Error ◽  
Temperature And Precipitation ◽  
Discharge Temperature ◽  
Neuro Fuzzy

In this study, the discharge of Ikpoba River was modelled and forecasted using adaptive neuro-fuzzy inference system (ANFIS). The river daily discharge, temperature and precipitation data sets from year 1991 to 1995 were used. In applying the ANFIS, five models stages; model-1, model-2, model-3, model-4 and model-5 were created using MATLAB. Model-1 to 4 were created using only the river discharge data, while model-5 was created by incorporating temperature and precipitation to cater for the effect of climate change into model-4. Five performance evaluation criteria, coefficient of correlation (R), coefficient of determination (R2), mean square error (MSE), modelling efficiency (E) and index of agreement (IOA) were used for comparative analysis. The results showed that though Model 1 to 4 were able to predict the river discharge accurately, model-5 (when the effect of climate change was incorporated) performed better than the other four models with only discharge data. The training phase in model-5 showed an over-estimation of 0.043% of the observed target output sets while an over-estimation of 0.044% was observed in the testing phase. These are within acceptable error tolerance of +/-10% for data validation. This information is useful for integrated water resources planning and management.

Farm, food and resource issues: politics and dryland salinity

2005 ◽  
Vol 45 (11) ◽  
pp. 1471 ◽  
Author(s):  
D. J. Pannell
Keyword(s):  
Rural Areas ◽  
Agricultural Development ◽  
Catchment Management ◽  
State Governments ◽  
Dryland Salinity ◽  
Economic Changes ◽  
Specific Investments ◽  
Political Forces ◽  
Salinity Management

Political forces make it difficult to develop effective and efficient policies for dryland salinity. The politics of the day have had major influences on salinity and salinity-related policy, beginning with the clearing of land for agricultural development. Tensions affecting salinity policy include urban political power v. rural salinity; short-term politics v. long-term salinity; crisis-driven politics v. slow and inexorable salinity; simplistic and uniform political solutions v. complex and diverse salinity problems; the need for winners in politics v. the reality of losers from effective salinity policy; east v. west; and national v. state governments. These tensions will interact with our improving scientific knowledge of salinity and ongoing social and economic changes in rural areas to shape future salinity policies. Prospects for changes in salinity policy and outcomes over the next 10 years are suggested, including the following possibilities: more carefully targeted and site-specific investments in salinity prevention; the beginnings of success of current research and development efforts to develop profitable new plant-based systems for salinity management; ongoing debate about the appropriate role for catchment management bodies for in salinity management; greater attention to the problem of salinity impacts on biodiversity and infrastructure; reduced attention to market-based instruments for salinity; and ongoing changes in the economics of agriculture, timber and energy influencing salinity outcomes and, potentially, salinity policy.

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