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Author: Raphael Muli Wambua Publisher: GRIN Verlag ISBN: 3668917477 Category : Technology & Engineering Languages : en Pages : 245
Book Description
Doctoral Thesis / Dissertation from the year 2016 in the subject Engineering - Civil Engineering, grade: 80.0, Egerton University, course: AGRICULTURAL ENGINEERING, language: English, abstract: Drought is a critical stochastic natural disaster that adversely affects water resources, ecosystems and people. Drought is a condition characterized by scarcity of precipitation and/or water quantity that negatively affects the global, regional and local land-scales. At both global and regional scales, drought frequency and severity have been increasing leading to direct and indirect decline in water resources. Increase in drought severity and frequency in the upper Tana River basin, Kenya, water resources systems have been adversely affected. Timely detection and forecasting of drought is crucial in planning and management of water resources. The main objective of this research was to formulate the most appropriate models for assessment and forecasting of drought using Indices and Artificial Neural Networks (ANNs) for the basin. Hydro-meteorlogical data for the period 1970-2010 at sixteen hydrometric stations was used to test the performance of the indices in forecasting of the future drought at 1, 3, 6, 9, 12, 18 and 24-months lead times, by constructing ANN models with different time delays. Drought conditions at monthly temporal resolution were evaluated using selected drought indices. The occurrence of drought was investigated using non-parametric Man-kendall trend test. Spatial distribution of drought severity was determined using Kriging interpolation techinique. In addition, a standard Nonlinear-Integrated Drought Index (NDI), for drought forecasting in the basin was developed using hydro-meteoroogical data for the river basin. The results of spaial drought show that the south-eastern parts of the basin are more prone to drought risks than the north-western areas. The Mann-Kendall trend test indicates an increasing drought trend in the south-eastern and no trend in north-western areas of the basin. Development of Surface Water Supply Index (SWSI) function, NDI and characteristic curves defining the return period and the probability of different drought magnitudes based on Drought Indices (DIs) was achieved. Drought Severity-Duration-Frequency (SDF) curves were developed. The formulated NDI tool can be adopted for a synchronized assessment and forecasting of all the three operational drought types in the basin. The results can be used in assisting water resources managers for timely detection and forecasting of drought conditions in prioritized planning of drought preparedness and early warning systems.
Author: Raphael Muli Wambua Publisher: GRIN Verlag ISBN: 3668917477 Category : Technology & Engineering Languages : en Pages : 245
Book Description
Doctoral Thesis / Dissertation from the year 2016 in the subject Engineering - Civil Engineering, grade: 80.0, Egerton University, course: AGRICULTURAL ENGINEERING, language: English, abstract: Drought is a critical stochastic natural disaster that adversely affects water resources, ecosystems and people. Drought is a condition characterized by scarcity of precipitation and/or water quantity that negatively affects the global, regional and local land-scales. At both global and regional scales, drought frequency and severity have been increasing leading to direct and indirect decline in water resources. Increase in drought severity and frequency in the upper Tana River basin, Kenya, water resources systems have been adversely affected. Timely detection and forecasting of drought is crucial in planning and management of water resources. The main objective of this research was to formulate the most appropriate models for assessment and forecasting of drought using Indices and Artificial Neural Networks (ANNs) for the basin. Hydro-meteorlogical data for the period 1970-2010 at sixteen hydrometric stations was used to test the performance of the indices in forecasting of the future drought at 1, 3, 6, 9, 12, 18 and 24-months lead times, by constructing ANN models with different time delays. Drought conditions at monthly temporal resolution were evaluated using selected drought indices. The occurrence of drought was investigated using non-parametric Man-kendall trend test. Spatial distribution of drought severity was determined using Kriging interpolation techinique. In addition, a standard Nonlinear-Integrated Drought Index (NDI), for drought forecasting in the basin was developed using hydro-meteoroogical data for the river basin. The results of spaial drought show that the south-eastern parts of the basin are more prone to drought risks than the north-western areas. The Mann-Kendall trend test indicates an increasing drought trend in the south-eastern and no trend in north-western areas of the basin. Development of Surface Water Supply Index (SWSI) function, NDI and characteristic curves defining the return period and the probability of different drought magnitudes based on Drought Indices (DIs) was achieved. Drought Severity-Duration-Frequency (SDF) curves were developed. The formulated NDI tool can be adopted for a synchronized assessment and forecasting of all the three operational drought types in the basin. The results can be used in assisting water resources managers for timely detection and forecasting of drought conditions in prioritized planning of drought preparedness and early warning systems.
Author: PhD Mutua (Rer. nat., Prof. Dr.-Ing. Benedict Mwavu) Publisher: ISBN: Category : Languages : en Pages : 0
Book Description
Climate change has continued to impact negatively on water resources globally. For instance, extreme weather conditions especially the drought phenomena have become frequent in Africa. This has prompted water engineers and hydrologists to formulate mitigation and adaptation measures to address these challenges. The frequency of drought event of a defined severity for a defined return period is fundamental in planning, designing, operating and managing water resources systems within a basin. This paper presents an analysis of the hydrological drought frequency for the upper Tana River basin in Kenya using the absolute Stream flow Drought Index (SDI) and modified Gumbel technique. The study used a 41-year (1970-2010) stream flow data and forecasted hydrological droughts for 2, 5, 10, 20, 50, 100, 200, 500 and 1000-year return periods in relation to the selected stream flows. The results provide an overview of drought trends within the river basin and therefore would be very useful in applying drought adaptation policies by water resource managers.
Author: Vitali Diaz Mercado Publisher: CRC Press ISBN: 100061283X Category : Science Languages : en Pages : 135
Book Description
Studies of drought have increased in light of new data availability and advances in spatio-temporal analysis. However, the following gaps still need to be filled: 1) methods to characterise drought that explicitly consider its spatio-temporal features, such as spatial extent (area) and pathway; 2) methods to monitor and predict drought that include the above-mentioned characteristics and 3) approaches for visualising and analysing drought characteristics to facilitate interpretation of its variation. This research aims to explore, analyse and propose improvements to the spatio-temporal characterisation of drought. Outcomes provide new perspectives towards better prediction. The following objectives were proposed. 1) Improve the methodology for characterising drought based on the phenomenon’s spatial features. 2) Develop a visual approach to analysing drought variations. 3) Develop a methodology for spatial drought tracking. 4) Explore machine learning (ML) techniques to predict crop-yield responses to drought. The four objectives were addressed and results are presented. Finally, a scope was formulated for integrating ML and the spatio-temporal analysis of drought. Proposed scope opens a new area of potential for drought prediction (i.e. predicting spatial drought tracks and areas). It is expected that the drought tracking and prediction method will help populations cope with drought and its severe impacts.
Author: Tae-Woong Kim Publisher: MDPI ISBN: 3039368060 Category : Technology & Engineering Languages : en Pages : 168
Book Description
This Special Issue is a platform to fill the gaps in drought risk analysis with field experience and expertise. It covers (1) robust index development for effective drought monitoring; (2) risk analysis framework development and early warning systems; (3) impact investigations on hydrological and agricultural sectors; (4) environmental change impact analyses. The articles in the Special Issue cover a wide geographic range, across China, Taiwan, Korea, and the Indo-China peninsula, which covers many contrasting climate conditions. Hence, the results have global implications: the data, analysis/modeling, methodologies, and conclusions lay a solid foundation for enhancing our scientific knowledge of drought mechanisms and relationships to various environmental conditions.
Author: Smakhtin, Vladimir U Publisher: IWMI ISBN: 9290905786 Category : Droughts Languages : en Pages : 32
Book Description
This paper reviews the existing indices which have been developed for monitoring and quantitative assessment of droughts, and analyzes their applicability for drought prediction and management in the specific context of South Asia. It further describes the suite of routines, which have been developed for automated estimation, display and analyses of various drought indices. The suite forms part of the comprehensive computer package, developed earlier and designed to perform the multitude of water resources analyses and hydrometeorological data processing. The seven-step procedure of setting up and running a typical drought-assessment application is described in detail.
Author: Zekâi Şen Publisher: Elsevier ISBN: 0128024224 Category : Science Languages : en Pages : 485
Book Description
Applied Drought Modelling, Prediction, and Mitigation provides a practical guide to new and recent methodologies for drought characterizations, change modeling, down-scaling, and future predictions. The modeling procedures covered by the book include recent advancements in regional drought extent, coverage, intensity, and water deficit predictions, which are increasingly significant given current climate change impacts on water resources. Each modeling procedure is explained theoretically prior to the mathematical derivation, and includes book examples, exercises, and case studies that supplement the applied and practical material, thus making the approaches accessible and applicable to the reader. - Presents new and recent methodologies for drought characterizations, change modeling, down-scaling, and future predictions - Includes online modeling tools to help readers quickly solve drought related problems - Presents methodologies, including drought features (duration, intensity, and magnitude) at any desired risk level - Include case studies from arid and semi-arid regions
Author: Raphael Muli Wambua
Author: Raphael Muli Wambua
Author: PhD Mutua (Rer. nat., Prof. Dr.-Ing. Benedict Mwavu)
Author: Vitali Diaz Mercado
Author: Yi Li
Author: Donald Owele Akanga
Author: Taylor & Francis Group
Author: Tae-Woong Kim
Author: Alireza Shahabfar
Author: Smakhtin, Vladimir U
Author: Zekâi Şen