Impact of land use on river basin water balance: a case study of the Modder River Basin, South Africa PDF Download
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Author:
Publisher: IWMI
ISBN: 9290906324
Category : Land use
Languages : en
Pages : 39
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Book Description
Author:
Publisher: IWMI
ISBN: 9290906324
Category : Land use
Languages : en
Pages : 39
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Book Description
Author: François Molle
Publisher: IWMI
ISBN: 9290906529
Category : Water-supply
Languages : en
Pages : 42
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Book Description
The concept of a river basin as a management or planning unit has gone through several stages and is in a state of flux.
Author:
Publisher: CIMMYT
ISBN: 9290906782
Category : Conservation tillage
Languages : en
Pages : 59
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Book Description
The recent stagnation of productivity growth in the irrigated areas of the Indo-Gangetic Plains of South Asia has led to a quest for resource conserving technologies that can save water, reduce production costs and improve production. The present synthesis of two detailed country studies confirmed widespread adoption of zero tillage (ZT) wheat in the rice-wheat systems of India's Haryana State (34.5% of surveyed households) and Pakistan's Punjab province (19%). The combination of a significant "yield effect" and "cost-saving effect" makes adoption worthwhile and is the main driver behind the rapid spread and widespread acceptance of ZT in Haryana, India. In Punjab, Pakistan, adoption is driven by the significant ZT-induced cost savings for wheat cultivation. Thus, the prime driver for ZT adoption is not water savings or natural resource conservation but monetary gain in both sites. Water savings are only a potential added benefit. ZT adoption for wheat has accelerated from insignificant levels from 2000 onwards in both sites. Geographic penetration of ZT is far from uniform, suggesting the potential for further diffusion, particularly in Haryana, India. Diffusion seems to have stagnated in the Punjab study area, and further follow-up studies are needed to confirm this. The study also revealed significant dis-adoption of ZT in the survey year: Punjab, Pakistan 14 percent and Haryana, India 10 percent. Better understanding the rationale for dis-adoption merits further scrutiny. Our findings suggest that there is no clear single overarching constraint but that a combination of factors is at play, including technology performance, technology access, seasonal constraints and, particularly in the case of Punjab, Pakistan, the institutional ZT controversy. In terms of technology performance, the relative ZT yield was particularly influential: dis-adopters of ZT reporting low ZT yields as a major contributor to farmer disillusionment in Punjab, Pakistan and the lack of a significant yield effect in Haryana, India. In neither site did the ZT-induced time savings in land preparation translate into timelier establishment, contributing to the general lack of a yield increase. Knowledge blockages, resource constraints and ZT drill cost and availability all contributed to nonadoption. This suggests that there is potential to further enhance access to this technology and thereby its penetration. The study highlights that in both Haryana, India and Punjab, Pakistan ZT has been primarily adopted by the larger and more productive farmers. The structural differences between the adopters and non-adopters/dis-adopters in terms of resource base, crop management and performance thereby easily confound the assessment of ZT impact across adoption categories. This calls for the comparison of the ZT plots and conventional tillage plots on adopter farms. ZT-induced effects primarily apply to the establishment and production costs of the wheat crop. Both the Haryana, India and Punjab, Pakistan studies confirmed significant ZT-induced resource-saving effects in farmers' fields in terms of diesel and tractor time for wheat cultivation. Water savings are, however, less pronounced than expected from on-farm trial data. It was only in Haryana, India that there were significant ZT-induced water savings in addition to significant yield enhancement. The higher yield and water savings in Haryana, India result in significantly Abstract vi higher water productivity indicators for ZT wheat. In both sites, there are limited implications for the overall wheat crop management, the subsequent rice crop and the rice-wheat system as a whole. The ZT-induced yield enhancement and cost savings provide a much needed boost to the returns to, and competitiveness of, wheat cultivation in Haryana, India. In Punjab, Pakistan, ZT is primarily a cost-saving technology. Based on these findings the study provides a number of recommendations for research and development in South Asia's rice-wheat systems.
Author: G.D. Jordaan
Publisher: UJ Press
ISBN: 1920383174
Category : Education
Languages : en
Pages : 160
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Book Description
Modelling as Research Methodology is written for the scientist and student researching the (expected) functioning of systems under specified conditions. As such, it represents an introduction to the use of modelling in natural, human and economical sciences. The book is divided into two sections. The first section illustrates the universal nature of modelling as aid to the researcher. In the second section, several typical examples of modelling are described.
Author: A. Neiland
Publisher: IWMI
ISBN: 9290906510
Category : Fisheries
Languages : en
Pages : 50
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Book Description
Author: Yiping Li
Publisher: Springer Nature
ISBN: 9819995817
Category :
Languages : en
Pages : 248
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Book Description
Author: Nnenesi A. Kgabi
Publisher: AOSIS
ISBN: 1928523838
Category : Science
Languages : en
Pages : 272
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Book Description
The scholarly theme of the book lends itself to the discipline of earth and atmospheric sciences, with a specific focus on water-climate studies. The book is a scholarly discourse by researchers in the natural sciences, including Hydrologists, Climate Scientists, Environmental Engineers and Water Scientists. The purpose of the book is to address the limited complementarity between the water and climate studies; which is crucial in promoting scientific research that informs policy decisions and implementation of water security plans. The chapters were selected to represent water-climate models and policy research conducted in different river basins in the arid and semi-arid environments. Therefore, the water-climate management tools highlighted in this book include General Circulation Models (GCMs), Coupled Model Inter-comparison Project Phase 5 (CMIP5), Soil and Water Assessment Tool (SWAT), Africa Flood and Drought Monitor (AFDM), Extreme Precipitation Events (EPEs), R ClimDex, Mixed strategy game models, Standard Precipitation Indices (SPIs), Water Evaluation and Planning System (WEAP), Penman Calculator, and Saturated Volume Fluctuation (SVF).
Author: Richard N. Boisvert
Publisher: IWMI
ISBN: 9290906480
Category : Agriculture and state
Languages : en
Pages : 48
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Book Description
Author: Renate Van Heerden
Publisher:
ISBN:
Category : Climatic changes
Languages : en
Pages : 0
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Book Description
Land-use changes and climate variability are known to affect environmental processes, and fluvio-marine environments tend to be extremely sensitive to these impacts. Hydrological models have been introduced in numerous studies to explore the responses in catchment processes. Spatially distributed rainfall-runoff models provide a more holistic view of the hydrological behaviour under different environmental conditions. However, the use of hydrological models in South African studies which investigate the impacts of climate and land-use change on discharge are scarce, and only a limited number have investigated the impact of climate and land use on catchment processes. What is of more relevance and importance in real-world applications is the differentiation between the respective roles of climate and land use on specific catchments. This study implements Spatial Tools for River basin Environmental Analysis and Management (STREAM), a GIS-based water-balance model, to investigate the major causes in change of discharge volume in the Amatikulu and Nyoni catchments (KwaZulu-Natal, South Africa). River and coastal morphological changes have also been observed in the recent past. This study proposed that land-use changes and climate variability have the largest influence on the change in discharge volumes; however, the exact extent needs investigation. Climate and land-use data for the period 1964-2015 are used for the model simulations. It has been found that land-use changes have had no significant impact on the discharge for this period, while climate has had the larger effect. Climatic scenarios corresponding to projected climate change have been investigated, and have shown that a 5AÌ2℗ʻC increase in temperature would have the largest influence on discharge compared to the observed changes in land use.
Author: Natasha Holland
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Book Description
