Great Ruaha River Research Articles

The Effect of Reduced Water Availability in the Great Ruaha River on the Vulnerable Common Hippopotamus in the Ruaha National Park, Tanzania.

In semi-arid environments, ‘permanent’ rivers are essential sources of surface water for wildlife during ‘dry’ seasons when rainfall is limited or absent, particularly for species whose resilience to water scarcity is low. The hippopotamus (Hippopotamus amphibius) requires submersion in water to aid thermoregulation and prevent skin damage by solar radiation; the largest threat to its viability are human alterations of aquatic habitats. In the Ruaha National Park (NP), Tanzania, the Great Ruaha River (GRR) is the main source of surface water for wildlife during the dry season. Recent, large-scale water extraction from the GRR by people upstream of Ruaha NP is thought to be responsible for a profound decrease in dry season water-flow and the absence of surface water along large sections of the river inside the NP. We investigated the impact of decreased water flow on daytime hippo distribution using regular censuses at monitoring locations, transects and camera trap records along a 104km section of the GRR within the Ruaha NP during two dry seasons. The minimum number of hippos per monitoring location increased with the expanse of surface water as the dry seasons progressed, and was not affected by water quality. Hippo distribution significantly changed throughout the dry season, leading to the accumulation of large numbers in very few locations. If surface water loss from the GRR continues to increase in future years, this will have serious implications for the hippo population and other water dependent species in Ruaha NP.

Uncertain hydrological modelling: application of the Pitman model in the Great Ruaha River basin, Tanzania

Uncertainty analysis has become the standard approach to hydrological modelling, but has yet to be effectively used in practical water resources assessment. This study of the Great Ruaha River basin in Tanzania is based on the use of regional estimates of mean runoff, groundwater recharge and three flow points on flow duration curves (FDCs) to constrain ensemble outputs from the Pitman monthly model using Monte Carlo parameter sampling. The constraint bounds were quantified from gauged data available for 26 sub-basins together with assumptions about the spatial variations in hydrological response using limited physical sub-basin property and climate data. The results are encouraging in that the simulated FDC ranges bracket the observed curves at two gauging stations downstream of many ungauged sub-basins that are important sites for water resources development decision making. Further work is required to refine the constraint bounds, the input parameter sets and climate data and achieve a more robust model of the basin.Editor D. Koutsoyiannis; Guest editor G. Mahé

Interpolation of daily raingauge data for hydrological modelling in data sparse regions using pattern information from satellite data

In order to cope with a severe reduction of the raingauge network in the Great Ruaha River basin over the past 30 years, an interpolation scheme using spatial patterns from satellite images as covariate has been evaluated. The regression-based interpolation attempts to combine the advantages of accurate rainfall amounts from raingauge records with the unique spatial pattern information obtained from satellite-based rainfall estimates. A spatial pattern analysis reveals that the simple interpolation of the sparse current raingauge network compares very poorly to the pattern originating from the much denser historic network. In contrast, the rainfall datasets that include patterns from satellite data show good correlation with the historic pattern. The evaluation based on hydrological modelling showed similar and good performance for all rainfall products, including raingauge records, whereas the purely satellite-based product performed poorly.

Large mammals in Ruaha National Park, Tanzania, dig for water when water stops flowing and water bacterial load increases

As water is essential for life, animals have adaptations that increase their ability to survive during periods of water shortage. Accessing water by digging is one behavioural adaptation to water shortage used by some African mammals. Digging might also provide access to higher quality water below ground when surface water quality is poor. We investigated the digging of waterholes by wildlife in the Ruaha National Park (NP), in central Tanzania, during three dry seasons (June to November from 2011 to 2013). We monitored surface water availability and water quality at 10 sites along the Great Ruaha River (GRR) and eight non-GRR sites. We used camera-traps and direct observations to determine when and where digging to access water occurred. Elephant (Loxodonta africana), plains zebra (Equus quagga), warthog (Phacochoerus africanus) and yellow baboon (Papio cynocephalus) dug waterholes and a further four species drunk from these holes. Waterholes were dug later in the dry season along the GRR (October) than at other sites (July). The likelihood of digging and drinking from waterholes was lower along the GRR than at non-GRR sites and did not depend on the absence of surface water but increased when surface water stopped flowing. Digging of waterholes was also significantly more likely when the bacterial load in available surface water increased but was independent of salinity levels. Escherichia coli load, indicative of faecal contamination, significantly increased with total aerobic bacterial load. Our results suggest that digging is an adaptation to avoid the ingestion of poor quality surface water highly contaminated with faeces, and thereby possibly also potentially pathogenic microbes, in addition to providing access to water when surface water is absent. Our findings also highlight (1) the essential role of the GRR as the key water source for wildlife in the Ruaha NP during the dry season, and (2) that maintenance of water flow throughout the dry season is essential to prevent deterioration of water quality in the GRR.

Revision of the Amphilius jacksonii complex (Siluriformes: Amphiliidae), with the descriptions of five new species.

The Amphilius jacksonii complex is revised, and five new species are described: A. ruziziensis n. sp. from the Ruzizi River drainage and northeastern tributaries of Lake Tanganyika; A. pedunculus n. sp. from the Malagarasi River drainage, Lake Rukwa basin, and upper Great Ruaha River drainage, Rufiji basin; A. frieli n. sp. from the upper Congo basin; A. crassus n. sp. from the Rufiji and Wami basins; and A. lujani n. sp. from the Lake Kyogo drainage, northeastern tributaries of Lake Victoria, and the Lake Manyara basin.

Geographical ancestry of Lake Malawi's cichlid fish diversity.

The Lake Malawi haplochromine cichlid flock is one of the largest vertebrate adaptive radiations. The geographical source of the radiation has been assumed to be rivers to the south and east of Lake Malawi, where extant representatives of the flock are now present. Here, we provide mitochondrial DNA evidence suggesting the sister taxon to the Lake Malawi radiation is within the Great Ruaha river in Tanzania, north of Lake Malawi. Estimates of the time of divergence between the Lake Malawi flock and this riverine sister taxon range from 2.13 to 6.76 Ma, prior to origins of the current radiation 1.20-4.06 Ma. These results are congruent with evaluations of 2-3.75 Ma fossil material that suggest past faunal connections between Lake Malawi and the Ruaha. We propose that ancestors of the Malawi radiation became isolated within the catchment during Pliocene rifting that formed both Lake Malawi and the Kipengere/Livingstone mountain range, before colonizing rivers to the south and east of the lake region and radiating within the lake basin. Identification of this sister taxon allows tests of whether standing genetic diversity has predisposed Lake Malawi cichlids to rapid speciation and adaptive radiation.

Nitrogen and Phosphorus Dynamics in the Waters of the Great Ruaha River, Tanzania

This study assessed the levels of nitrogenous (ammonia, nitrite and nitrate) and phosphate compounds in the water column in the Great Ruaha River (GRR) in response to natural and human pressures. Water were sampled using Teflon capped plastic containers and analysed using standard methods. High levels of ammonia were observed in the Mtera dam and low in the GRR and its tributaries as well as at Ruaha Mbuyuni. Nitrite levels were observed only in Mswiswi and Luwosi tributaries in the upstream and in the Mtera and Ruaha Mbuyuni in the downstream. High levels of nitrite were observed in the Mtera dam probably due to increased microbial activity. Levels of nitrates were high in the Mtera dam and in the Mswiswi and Lunwa tributaries and low in the Little Ruaha, Ruaha Mbuyuni and in other tributaries. Nitrate levels were increasing from the tributaries to the main river and later decreasing at Ruaha Mbuyuni probably indicative of some changes in land cover, land use, soil type and groundwater level. Observed levels of phosphate followed an irregular pattern and were relatively were high probably due to anthropogenic activities and absence of Ca, Mg, Al and Fe minerals that can precipitate phosphate. Levels of nitrogen and phosphorus in the GRR were lower than the US EPA and Health Canada set standards, indicative of a natural source. Principal Component Analysis (PCA) indicate that the nitrite and ammonia are so closely related to each other than to nitrate, indicating probably that most nitrites originate from the nitrification of ammonia than the denitrification of nitrate. Similarly, nitrate and phosphate were observed in the same principal component clearly indicative of the same source, which could be fertiliser application in agricultural fields. However, increasing agricultural and livestock activities as aggravated by increasing human population pose a threat on the future dynamics of the nitrogen and phosphorus in the area.

New perspectives in ecosystem services science as instruments to understand environmental securities.

As societal demand for food, water and other life-sustaining resources grows, the science of ecosystem services (ES) is seen as a promising tool to improve our understanding, and ultimately the management, of increasingly uncertain supplies of critical goods provided or supported by natural ecosystems. This promise, however, is tempered by a relatively primitive understanding of the complex systems supporting ES, which as a result are often quantified as static resources rather than as the dynamic expression of human-natural systems. This article attempts to pinpoint the minimum level of detail that ES science needs to achieve in order to usefully inform the debate on environmental securities, and discusses both the state of the art and recent methodological developments in ES in this light. We briefly review the field of ES accounting methods and list some desiderata that we deem necessary, reachable and relevant to address environmental securities through an improved science of ES. We then discuss a methodological innovation that, while only addressing these needs partially, can improve our understanding of ES dynamics in data-scarce situations. The methodology is illustrated and discussed through an application related to water security in the semi-arid landscape of the Great Ruaha river of Tanzania.

Effect of elephant browsing on selected species of <i>Acacia</i> along the great Ruaha River in Ruaha National Park, Tanzania

Elephant damage was assessed in 1,007 Acacia trees and responses between Acacia tortilis and A. kirkii in Ruaha National park were compared in 30 transects randomly placed in 38.8 km2 on the northern bank of Great Ruaha River (GRR) basing on six browsing categories and four debarking classes. There was no significant difference in browsing (F1, 10 = 0.6, p>0.05) and debarking (F1, 6 = 0.16, p > 0.05) between A. kirkii and A. tortilis. Trees were classified into three height and twelve diameter classes. About 3613 trees <1 m in height represented response in addition to coppices. The difference between the two species was observed only in regeneration potential (F1,58 = 41.4, p < 0.05). In addition, low regeneration potential, severely browsed trees and restricted distribution made A. kirkii more vulnerable to elephant feeding compared to A. tortilis. The high A. tortilis regeneration potential suggests that the study area could become an Acacia bushland or woodland if fire is controlled. Further studies need to investigate, the suppressed regeneration of Acacia trees at Msembe, variations in vegetation utilization along the GRR and effects of fire and small browsers on Acacia species including monitoring of vegetation and animal trends.Key words: Elephants, Acacia, Tree damage, Regeneration, Ruaha River

Climate Variability, Impacts and Adaptation Strategies: The Case of Mbeya and Makete Districts in Great Ruaha Catchment in Tanzania

This paper presented key findings from the study which aimed to assess the impacts of climate variability and local adaptation strategies in selected villages of Mbeya and Makete Districts located in the most upper Great Ruaha River catchment in Southern Tanzania. Together, the study districts cover a wide range of climate change related hazards. Both qualitative and quantitative methods are used for data collection and analysis. The study shows that, there is significant change in pattern and amount of rainfall contributing to water stress, making people more vulnerable. Local communities are adapting to spatial and temporal climate variability, with varying degrees of success. Traditional smallholder irrigated systems used as adaptation strategies for crop production are characterized by low water use efficiency and high water losses. This implies that, if irrigation is managed properly, it can lead to sustainable increases in small farmer’s productivity and income, thus alleviating rural poverty and enhancing environmental management objectives.

Environmental flow assessment as a tool for achieving environmental objectives of African water policy, with examples from East Africa

Africa has set ambitious targets for development of water resources over the coming decades. Africa Water Vision 2025 calls for a doubling of irrigated agriculture and a five-fold increase in water use for agriculture, industry, and hydropower. The ambitious development targets are framed in the context of integrated water resources management, which also seeks to simultaneously allocate sufficient water for environmental sustainability. Over the past two decades scientists have devised a number of practical and robust approaches to determine environmental water requirements in rivers and wetlands based on the objectives set in water planning. We review the most widely applied approaches to assess environmental flow requirements and consider their application in Africa through case studies in the transboundary Mara River basin of Kenya and Tanzania and the Great Ruaha River basin in Tanzania.

The role of vegetation in the water budget of the Usangu wetlands, Tanzania

The Usangu wetlands were severely degraded over the last twenty years by cattle and the shortage of water due to rice irrigation upstream. The eastern Usangu wetlands that were previously perennial dried out in 2000 and 2002 in the dry season. Following the removal of cattle in 2006 from the eastern Usangu wetlands, perennial wetlands has re-established itself and in 2011 the vegetation had recovered and covered about 95 % of the wetted surface mainly as floating vegetation. These wetlands are the source of water of the Great Ruaha River and the volume of water entering the river has nearly doubled after cattle removal. We suggest that this may be due to the shading effect of the floating vegetation reducing the loss of water through net evaporation to about 0.5 cm day−1 as opposed to about 1 cm day−1 for open water evaporation in this tropical climate. This suggests the important role of the biology in controlling the water budget. By contrast cattle and rice farms have not been removed from the western Usangu wetlands, located upstream, where the wetlands are now reduced to small areas fringing the rivers. We suggest that the western Usangu wetlands should also be restored in order to further increase flows in the Great Ruaha River. At the same time water governance in the catchments and irrigation areas upstream of Usangu wetlands is also urgently required because present water yields are insufficient to meet the hydroelectric needs of Tanzania, the water users all along the river, as well as the important coastal wetlands associated with the Rufiji Delta during a drought year.

The not-so-Great Ruaha and hidden histories of an environmental panic in Tanzania

Water is one of the world's most contested resources, and Africa's river basins are no exception. In December 1993 the Great Ruaha River upstream of Tanzania's Mtera Dam stopped flowing for the first time in living memory. This became a matter of national concern in 1995 when electricity shortages and rationing in Dar es Salaam were blamed by the national power supply company (TANESCO) on the continuing drying-up of the Great Ruaha. Since then different institutions and interest groups have sought to explain the river's increasing seasonality, focusing on resource use in and around its immediate source, the Usangu wetland, and laying the blame on different groups of resource users. In 1998 the core of the wetland (Ihefu) was gazetted as part of a new game reserve, and fishermen and livestock keepers were forcibly removed. Increasing government concern over power shortages culminated in the mass expulsion in 2006–07 of livestock keepers and their cattle from Usangu and Mbarali District, large parts of which were to be incorporated in an expanded Ruaha National Park. This was the largest eviction of its kind in recent Tanzanian history, widely condemned by NGOs and in the national and international media. This article examines in detail the development of the environmental panic and events which led to this eviction, highlighting the behind-the-scenes role played by actors and interests in the public and private sectors in fostering the panic and its controversial outcome.

Assessing the Hydrological Conditions of the Usangu Wetlands in Tanzania

Although wetlands make up less than 10% of Tanzania, their “critical, life support, ecosystem services” sustain over 95% of lives, of wildlife and of livestock. They provide security as sources of food, water, energy, economy and livelihoods, therefore, the aim of this paper is to address the current hydrologic conditions of Usangu wetlands. Several approaches were used in the collection of data for analysis. Both primary and sec- ondary data was collected and analysed. The key finding shows that, the overall area of the Usangu Wetlands is divided into two main portions, the Eastern Wetland and the Western Wetland, the core wetland, the Ihefu Swamp varies between 30 and 65 km2, whereas the seasonally wetted areas varies between 260 and 1800 km2. Major perennial rivers which feed the Ihefu swamp in Usangu wetlands include Kimani, Mbalali, Ndembera and the Great Ruaha River. The contribution from Mbalali River ranges between 69.17% and 47.78%; from Ndembera River ranges between 25% and 13.83%; from Kimani River ranges between 25% and 8.33% and from Great Ruaha River contribution ranges 24.0% and 2.96%. The irrigated agriculture is most important as a user of water and impacts most heavily on wetlands. Abstraction of water for agriculture is leading to dried up rivers, falling ground water tables, salinated soil and polluted waterways.

Vulnerability of People’s Livelihoods to Water Resources Availability in Semi Arid Areas of Tanzania

In semi-arid areas of Tanzania vulnerability context is depicted as the starting component for policy process analysis through the sustainable livelihood approach. Giving vulnerability a high prominence in this analysis allowed the research to consider all kinds of vulnerabilities as central issues to the ways in which livelihoods are shaped. Hence the Sustainable Livelihood framework was used in this research as the comprehensive framework for assessing the contributing factors to limited water resources availability to sustain people’s livelihoods. The study revealed that, changes in the quantity, timing, intensity and duration of rainfall as a result of climate change contributes to greater water stress and making people more vulnerable. Due to over-abstraction upstream of the Great Ruaha River, it implies that, people depending on the water resources downstream of the Great Ruaha River catchment are vulnerable. Their livelihoods are at risks as they don’t have water for irrigation and other economic activities. The study also revealed that, both vulnerability and livelihood strategies are derived through natural water availability which features droughts, climate change and the link between water availability, agricultural production, and outcomes.

Climate Change Impacts, Local Knowledge and Coping Strategies in the Great Ruaha River Catchment Area, Tanzania

Climate change has profound implications for managing freshwater resources and species dependent on those resources. Water is an essential component of the life support system of the earth, and a basic resource for socio-economic development. The Great Ruaha River Catchment Area is a dynamic and complex ecosystem requiring inclusion climate change adaptation in the management of the freshwater and natural resources available to reduce the severity of climate change impacts. Rainfall has decreased considerably during the last 10 - 30 years, and characterised by high interannual variability, seasonal shifts and variable seasonal distribution with unpredictable onset and ending of rains and shortened growing seasons. Temperature has increased considerably during this period causing increased evapotranspiration losses and incidences of pest and diseases. The freshwater of Ruaha River and it tributaries are vulneable to changing climate, such as drought, which can negatively impact on the livelihoods of the people through de- creased crop and livestock production, and on local biodiversity. The changing climate has had negative impacts on, among other aspects, land use and water shortages for irrigation, livestock and domestic uses. This has compelled riparian communities in the catchment to devises coping strategies including practicing irrigation to provide supplementary water to crops, using drought tolerant crop varieties, rationing of irrigation water in farmlands, wetland cultivation, and diversification to non-agricultural activities. Despite the existence of many indicators used for local climate forecasting, there are limitations to local adaptation, including among others, poverty, institutional aspects and limited integration of climate adaptation in various sectors. The bulk of indigenous knowledge could be integrated into formal adaptation planning, and may be important components of environmental conservation at the local level.

A review of the water crisis in Tanzania's protected areas, with emphasis on the Katuma River—Lake Rukwa ecosystem

Several cases of the developing water crisis in semi-arid regions of Tanzania are described. Some cases have transboundary causes. These include Lake Victoria and the riparian population as a result of hydroelectricity developments in Uganda, the Serengeti ecosystem threatened by deforestation of the Mau forest and irrigation in Kenya, and several national parks threatened by irrigation projects within Tanzania. Some of these developments are given national priorities like in case of the Great Ruaha River. Other irrigation projects are driven by the local population to combat poverty. Most of these developments are in breach of state laws because there is no consideration of minimal environmental flows and all have profound negative impacts on people and wildlife downstream. The paper describes the previously unreported case of irrigation in the upper Katuma River that flows into Lake Rukwa, which lead to poverty increase, environmental degradation and a decrease in ecosystem services provision downstream. Governance at the watershed scale in a framework compatible with ecohydrology principles is needed. Such solutions are proposed.

Extrapolating effects of conservation tillage on yield, soil moisture and dry spell mitigation using simulation modelling

There is big effort to disseminate conservation tillage practices in Tanzania. Despite wide spread field demonstrations there has been some field experiments meant to assess and verify suitability of the tillage options in local areas. Much of the experiments are short lived and thus long term effects of the tillage options are unknown. Experiments to study long term effects of the tillage options are lacking because they are expensive and cannot be easily managed. Crop simulation models have the ability to use long term weather data and the local soil parameters to assess long term effects of the tillage practices. The Agricultural Production Systems Simulator (APSIM) crop simulation model; was used to simulate long term production series of soil moisture and grain yield based on the soil and weather conditions in Mkoji sub-catchment of the great Ruaha river basin in Tanzania. A 24 year simulated maize yield series based on conventional tillage with ox-plough, without surface crop residues (CT) treatment was compared with similar yield series based on conservation tillage (ox-ripping, with surface crop residues (RR)). Results showed that predicted yield averages were significantly higher in conservation tillage than in conventional tillage ( P < 0.001). Long term analysis, using APSIM simulation model, showed that average soil moisture in the conservation tillage was significantly higher ( P < 0.05) (about 0.29 mm/mm) than in conventional tillage (0.22 mm/mm) treatment during the seasons which received rainfall between 468 and 770 mm. Similarly the conservation tillage treatment recorded significantly higher yields (4.4 t/ha) ( P < 0.01) than the conventional tillage (3.6 t/ha) treatment in the same range of seasonal rainfall. On the other hand there was no significant difference in soil moisture for the seasons which received rainfall above 770 mm. In these seasons grain yield in conservation tillage treatment was significantly lower (3.1 kg/ha) than in the conventional tillage treatment (4.8 kg/ha) ( P < 0.05). Results also indicated a probability of 0.5 of getting higher yield in conservation than in conventional tillage practice. The conservation tillage treatment had the ability to even-out the acute and long intra-seasonal dry spells. For example a 36-days agricultural dry spell which occurred between 85th and 130th day after planting in the 1989/1990 season (in the CT treatment) was mitigated to zero days in the RR treatment by maintaining soil moisture above the critical point. Critical soil moisture for maize was measured at 0.55 of maximum soil moisture that can be depleted crop (0.55 D). It is concluded that conservation tillage practice where ripping and surface crop residues is used is much more effective in mitigating dry spells and increase productivity in a seasonal rainfall range of between 460 and 770 mm. It is recommended that farmers in the area adopt that type of conservation tillage because rainfall was in this range (460–770 mm) in 12 out of the past 24 years, indicating possibility of yield losses once in every 2 years.

The Root Causes of the Declining levels of Water in the Great Ruaha River, Tanzania

Water scarcity is increasingly becoming a critical socio-economic and political problem all over the world. Water for agriculture, domestic use, livestock keeping, industries, transportation and energy supply is becoming scarce, and the situation is worsening. Fighting over access to water is increasing in Tanzania. Although frequency of declining levels of water in the Great Ruaha River is increasing, our understanding of the factors and the dynamics that drive this scarcity is inadequate. This article notes that factors that cause declining levels of water are stronger than the forces that act to prevent it. Some factors take place at the local, national and international levels; and the interactions among them. It is important to understand the root causes and take participatory and holistic approaches in addressing water scarcity in the Great Ruaha River and surrounding areas.

Freshwater management and climate change adaptation: Experiences from the Great Ruaha River catchment in Tanzania

Adaptation to anthropogenic climate change is becoming vital to freshwater ecosystems and resource management, but climate adaptation can be purposeful or unintentional. This paper presents lessons from an assessment of an autonomous adaptation in the Great Ruaha River catchment in Tanzania following WWF intervention. The project was designed to address challenges resulting from natural resource use and existing levels of climate variability by changing water resource management. The study applied participatory methods and an open-ended questionnaire to collect data. The study found key adaptation benefits, including reduced vulnerability to drought and strengthened local water user associations and other regional institutions. As a result of the project interventions from 2003 to 2009, rural livelihoods became more profitable and water-sustainable, and local livelihood strategies were diversified. Regional ecosystems improved as a result of restoring river flows in some rivers, conservation of riparian vegetation and halting tree felling for charcoal production. As a result of these changes the communities and ecosystems in the Great Ruaha River catchment should be more resilient to emerging climate change impacts, yet the need for further physical interventions and institutional reform is identified. The study concludes that strengthening local institutions and capacity building are fundamental to climate change adaptation and sustainable freshwater management.