Assessment of water levels and the effects of climatic factors and catchment dynamics in a shallow subtropical reservoir, Manjirenji Dam, Zimbabwe

2018 ◽  
Vol 10 (3) ◽  
pp. 580-590 ◽  
Author(s):  
Beaven Utete ◽  
Tamuka Nhiwatiwa ◽  
Blessing Kavhu ◽  
Samuel Kusangaya ◽  
Nyashadzashe Viriri ◽  
...  

Abstract Natural water level fluctuations have associated effects on water quality and resident aquatic communities, although their impacts are magnified if the dams have other non-seasonal designated multiple uses. Research demonstrates that excessive water level fluctuations impair ecosystem functioning, ultimately leading to shifts between clear-water and turbid states in shallow lakes. However, these data lack for Manjirenji Dam in Zimbabwe, thus hampering efforts towards effective freshwater resources management in the shallow reservoir. This study analyzed water levels and their fluctuations, and assessed the effects of climatic factors and catchment dynamics using a combination of historical and remote sensed data for the shallow Manjirenji Dam in Zimbabwe. Time series and multiple regression analysis were used to determine water level trends, and the influence of catchment and climatic components in Manjirenji Dam. Lake levels have increased since construction, though their non-significant seasonal variation in the Manjirenji Dam reflects the overlapping effects of catchment and climatic variables. Despite the inferred high stability and resilience, the high fluctuation widths expose the dam to hydrodynamic and climate shocks which have major ecological and conservation implications. A climate change based integrated water resources management approach is necessary for sustainable water resources utilisation in the Manjirenji Dam.

2020 ◽  
Vol 92 (1) ◽  
pp. 41-54
Author(s):  
Adam Choiński ◽  
Jerzy Jańczak ◽  
Ptak Mariusz

Water-level fluctuations are among the primary factors determining the functioning of lakes. The volume to which lake basins are filled with water is of major importance to the courses of many processes and phenomena. A particular amount of water in a lake, and water-table stability, are also important from the point of view of human activity, as these elements help determine the quantity and accessibility of the water resources lakes have to offer, and therefore the possibilities for them to be used by different branches of the economy, e.g. industry, agriculture or tourism. The work detailed here is thus a presentation of trends as regards water-level fluctuations in 16 lakes in Poland, over the period 1956–2015. The study results, obtained for the first time in relation to such a long time scale and extending to around a dozen lakes, aim to point to the scale and direction of water-level fluctuations in times of the intensive transformation of the natural environment. They were obtained by reference to water-level observations made by the Institute of Meteorology and Water Management – National Research Institute (IMiGW-PIB). Specifically, data referring to the (November-October) hydrological year were analysed for trends as regards mean annual water levels using the Mann-Kendall test. Results point to major variability in the courses noted for these levels over the analysed multiannual period. Nevertheless, three overall situations could be designated from within the group of cases analysed, i.e. increase, decrease or lack of a trend. The first group includes Lakes Sławskie, Jamno, Łebsko, Nidzkie, and Studzieniczne (where increases were statistically significant at p=0.05); the second, Lakes Ostrzyckie and Ełckie (decreases significant at p=0.05); and the last group all remaining lakes, i.e. Charzykowskie, Jeziorak and Rajgrodzkie, Biskupińskie, Drwęckie and Białe, Gopło, Roś, and Wigry. It was, however, noted that in many cases analysed periods of alternating increase and decrease in water level were to be observed. The causes of such fluctuations were complex, but inter alia reflected droughts of several years’ duration, periods featuring higher-than-average precipitation, and local conditions. In general, water-level fluctuations in lakes result from natural and anthropogenic factors determining the hydrological conditions in catchments. And in the context of the lakes considered here, the courses of water-level fluctuations were mostly a reflection of local, rather than wider climatic conditions – a fact i.a. illustrated by the lack of cohesive regional designations. The situation is different from that of, for example, the thermal or ice regimes of Polish lakes, in relation to which observed similarities in properties are seen to be determined mainly by climatic factors. Information of this kind may be of key importance to the (quantitative and qualitative) management of water resources in the context of the climate change being observed currently.


Water ◽  
2020 ◽  
Vol 12 (12) ◽  
pp. 3424
Author(s):  
Juliet Katusiime ◽  
Brigitta Schütt

The water crisis can alternatively be called a governance crisis. Thus, the demand for good water governance to ensure effective water resources management and to attain specific water goals is growing. Many countries subscribe to the Integrated Water Resources Management (IWRM) approach to achieve this goal. The Integrated Water Resources Management approach aims to ensure a process that promotes the coordinated development and management of water, land, and related resources in a drainage basin to maximise economic and social welfare equitably without compromising the sustainability of vital ecosystems. The design of the Integrated Water Resources Management approach, including its pillars and principles, aspires to good water governance and effective resource management. However, empirical studies examining this hypothesis and analysing the impact of the Integrated Water Resources Management approach on water resources governance are limited, especially in developing countries. Therefore, we characterised and compared the water resources governance aspects of two catchments in Uganda’s Lake Albert basin. One of the catchments was exposed to integrated water resources management projects, while the other had no exposure to integrated water resources management projects. Some of the factors that supported the comparability of the two sites included spatial proximity linking into a related hydrological and social-economic setup, common water needs and belonging to the same water administration zone. Comparing both areas led us to analyse whether there was a difference in water resources governance actions, as well as in the quality of water resources governance, under the same overall water management and administrative zone. The data were based on field surveys using questionnaires and information guides in both catchments. The results show that the performance of water resources governance is markedly better in the catchment with Integrated Water Resources Management practices than the base catchment unaffected by these practices. Key themes examined include water resources governance styles, water resources governance systems presence, functionality, the performance of good governance principles, and water resources management effectiveness. The findings contribute to the aspirations for the promotion of integrated water management approaches for improved water resources governance, and the concept that the effectiveness of water resources management measures depends on governance effectiveness. Water governance is significant, as it spells out the power, rights, decisions, and priorities relating to given water resources and communities.


2003 ◽  
Vol 47 (7-8) ◽  
pp. 191-199
Author(s):  
F. Schlaeger ◽  
H. Schonlau ◽  
J. Köngeter

In this paper a concept of an integrated water quality model for a river catchment area is presented. The main focus is directed to the development of a water quality module for rivers. Necessary simplifications for calculation of hydraulics and water quality will be explained. Furthermore, by first simulation results possible applications of the model are presented.


2014 ◽  
Vol 11 (4) ◽  
pp. 4403-4431 ◽  
Author(s):  
T. A. Cochrane ◽  
M. E. Arias ◽  
T. Piman

Abstract. The rapid rate of water infrastructure development in the Mekong basin is a cause for concern due to its potential impact on fisheries and downstream natural ecosystems. In this paper we analyse the historical water levels of the Mekong River and Tonle Sap system by comparing pre and post 1991 daily observations from six stations along the Mekong mainstream from Chiang Sean (northern Laos), to Stung Treng (Cambodia), and the Prek Kdam station on the Tonle Sap River. Observed alterations in water level patterns along the Mekong are linked to temporal and spatial trends in water infrastructure development from 1960 to 2010. We argue that variations in historical climatic factors are important, but they are not the main cause of observed changes in key hydrological indicators related to ecosystem productivity. Our analysis shows that the development of mainstream dams in the upper Mekong basin in the post-1991 period have resulted in a significant increase of 7 day minimum (+91.6%), fall rates (+42%), and the number of water level fluctuations (+75) observed in Chiang Sean. This effect diminishes downstream until it becomes negligible at Mukdahan (northeast Thailand), which represents a drainage area of over 50% of the total Mekong Basin. Further downstream at Pakse (southern Laos), alterations to the number of fluctuations and rise rate became strongly significant after 1991. The observed alterations slowly decrease downstream, but modified rise rates, fall rates, and dry season water levels were still quantifiable and significant as far as Prek Kdam. This paper provides the first set of evidence of hydrological alterations in the Mekong beyond the Chinese dam cascade in the upper Mekong. Given the evident alterations with no precedence at Pakse and downstream, post-1991 changes can also be directly attributed to water infrastructure development in the Chi and Mun basins of Thailand. A reduction of 23 and 11% in the water raising and fall rates respectively at Prek Kdam provides evidence of a diminished Tonle Sap flood pulse in the post-1991 period. Given the observed water level alterations from 1991 to 2010 as a result of water infrastructure development, we can extrapolate that future development in the mainstream and the key transboundary Srepok, Sesan and Sekong subbasins will have an even greater effect on the Tonle Sap flood regime, the lower Mekong floodplain, and the delta.


2014 ◽  
Vol 18 (11) ◽  
pp. 4529-4541 ◽  
Author(s):  
T. A. Cochrane ◽  
M. E. Arias ◽  
T. Piman

Abstract. The rapid rate of water infrastructure development in the Mekong Basin is a cause for concern due to its potential impact on fisheries and downstream natural ecosystems. In this paper, we analyze the historical water levels of the Mekong River and Tonle Sap system by comparing pre- and post-1991 daily observations from six stations along the Mekong mainstream from Chiang Saen (northern Thailand), to Stung Treng (Cambodia), and the Prek Kdam station on the Tonle Sap River. Observed alterations in water level patterns along the Mekong are linked to temporal and spatial trends in water infrastructure development from 1960 to 2010. We argue that variations in historical climatic factors are important, but they are not the main cause of observed changes in key hydrological indicators related to ecosystem productivity. Our analysis shows that the development of mainstream dams in the upper Mekong Basin in the post-1991 period may have resulted in a modest increase of 30-day minimum levels (+17%), but significant increases in fall rates (+42%) and the number of water level fluctuations (+75%) observed in Chiang Saen. This effect diminishes downstream until it becomes negligible at Mukdahan (northeast Thailand), which represents a drainage area of over 50% of the total Mekong Basin. Further downstream at Pakse (southern Laos), alterations to the number of fluctuations and rise rate became strongly significant after 1991. The observed alterations slowly decrease downstream, but modified rise rates, fall rates, and dry season water levels were still quantifiable and significant as far as Prek Kdam. This paper provides the first set of evidence of hydrological alterations in the Mekong beyond the Chinese dam cascade in the upper Mekong. Given the evident alterations at Pakse and downstream, post-1991 changes could also be directly attributed to water infrastructure development in the Chi and Mun basins of Thailand. A reduction of 23 and 11% in the water raising and falling rates respectively at Prek Kdam provides evidence of a diminished Tonle Sap flood pulse in the post-1991 period. Given the observed water level alterations from 1991 to 2010 as a result of water infrastructure development, we can extrapolate that future development in the mainstream and the key transboundary Srepok, Sesan, and Sekong sub-basins will have an even greater effect on the Tonle Sap flood regime, the lower Mekong floodplain, and the delta.


Heliyon ◽  
2021 ◽  
Vol 7 (1) ◽  
pp. e05955
Author(s):  
Ben U. Ngene ◽  
Christiana O. Nwafor ◽  
Gideon O. Bamigboye ◽  
Adebanji S. Ogbiye ◽  
Jacob O. Ogundare ◽  
...  

Sign in / Sign up

Export Citation Format

Share Document