L. O. Olang

A Drought Monitoring and Forecasting System for Sub-Sahara African Water Resources and Food Security

Drought is one of the leading impediments to development in Africa. Much of the continent is dependent on rain-fed agriculture, which makes it particularly susceptible to climate variability. Monitoring drought and providing timely seasonal forecasts are essential for integrated drought risk reduction. Current approaches in developing regions have generally been limited, however, in part because of unreliable monitoring networks. Operational seasonal climate forecasts are also deficient and often reliant on statistical regressions, which are unable to provide detailed information relevant for drought assessment. However, the wealth of data from satellites and recent advancements in large-scale hydrological modeling and seasonal climate model predictions have enabled the development of state-of-the-art monitoring and prediction systems that can help address many of the problems inherent to developing regions. An experimental drought monitoring and forecast system for sub-Saharan Africa is described that is...

Analysis of spatio-temporal land cover changes for hydrological impact assessment within the Nyando River Basin of Kenya

The spatio-temporal changes in the land cover states of the Nyando Basin were investigated for auxiliary hydrological impact assessment. The predominant land cover types whose conversions could influence the hydrological response of the region were selected. Six Landsat images for 1973, 1986, and 2000 were processed to discern the changes based on a methodology that employs a hybrid of supervised and unsupervised classification schemes. The accuracy of the classifications were assessed using reference datasets processed in a GIS with the help of ground-based information obtained through participatory mapping techniques. To assess the possible hydrological effect of the detected changes during storm events, a physically based lumped approach for infiltration loss estimation was employed within five selected sub-basins. The results obtained indicated that forests in the basin declined by 20% while agricultural fields expanded by 16% during the entire period of study. Apparent from the land cover conversion matrices was that the majority of the forest decline was a consequence of agricultural expansion. The model results revealed decreased infiltration amounts by between 6% and 15%. The headwater regions with the vast deforestation were noted to be more vulnerable to the land cover change effects. Despite the haphazard land use patterns and uncertainties related to poor data quality for environmental monitoring and assessment, the study exposed the vast degradation and hence the need for sustainable land use planning for enhanced catchment management purposes.

Land Degradation of the Mau Forest Complex in Eastern Africa: A Review for Management and Restoration Planning

The Mau Forest Complex is the largest closed-canopy montane ecosystem in Eastern Africa. It encompasses seven forest blocks within the Mau Narok, Maasai Mau, Eastern Mau, Western Mau, Southern Mau, South West Mau and Transmara regions. The area is thus the largest water tower in the region, being the main catchment area for 12 rivers draining into Lake Baringo, Lake Nakuru, Lake Turkana, Lake Natron and the Trans-boundary Lake Victoria (Kundu et al., 2008; Olang & Furst, 2011). However, in the past three decades or so, the Mau Forest Complex (MFC) has undergone significant land use changes due to increased human population demanding land for settlement and subsistence agriculture. The encroachment has led to drastic and considerable land fragmentation, deforestation of the headwater catchments and destruction of wetlands previously existing within the fertile upstream parts. Today, the effects of the anthropogenic activities are slowly taking toll as is evident from the diminishing river discharges during periods of low flows, and deterioration of river water qualities through pollution from point and non-point sources (Kenya Forests Working Group [KFWG], 2001; Baldyga et al., 2007). Augmented by the adverse effects of climate change and variability, the dwindling land and water resources has given rise to insecurity and conflicts associated with competition for the limited resources. It is hence becoming urgently important that renewed efforts are focused on this region to avail better information for appropriate planning and decision support. Such a process will nonetheless, require an integrated characterization of the changing land and water flow regimes, and their concerned socio-economic effects on resource allocation and distribution (Krhoda, 1988; King, et al., 1999). Assessing the impacts of the environmental changes on water flow regimes generally require provision of time series meteorological, hydrological and land use datasets. However, like in a majority the developing countries, the MFC does not have good data infrastructure for monitoring purposes (Corey et al., 2007; Kundu et al., 2008). A majority of research studies in the area

Assessment of Land Cover Changes in Lake Olbolosat Region of the Central Kenyan Highlands using Landsat Satellite Imagery Aided by Indigenous Knowledge

Assessment of Land Cover Changes in Lake Olbolosat Region of the Central Kenyan Highlands using Landsat Satellite Imagery Aided by Indigenous Knowledge The region around Lake Olbolosat in the central Kenyan highlands has witnessed significant land-use changes, which are believed to be major cause of the dwindling Lake volumes. Very few studies have been carried out in the region due to limited observed in-situ data necessary for monitoring the land surface conditions. It is hence important that feasible, straightforward and cost-effective techniques are explored to asses the space and time variations with a view of providing the essential information for improved land and water management. This study investigated the land cover changes around Lake Olbolosat region using data obtained from Landsat satellite remote sensing.

The impact of land use change on runoff and peak flood discharges for the Nyando River in Lake Victoria drainage basin, Kenya

The effects of land use changes on the characteristics of floods in the Nyando River basin were investigated. Historical changes in the state of land cover were derived by processing multi-temporal Landsat images. The detected changes, together with other spatial datasets were subsequently used to estimate the physically based catchment and hydrologic model parameters for runoff generation and transformation, and for channel flow routing. The results obtained indicated that the basin experienced significant increases in peak discharge values, especially in the upstream areas where higher rates of deforestation were detected. Over the study period, the peak discharges increased by 16% in all of the 14 sub-catchments in the basin. Simulated flood volumes in the basin also increased by 10% over the same period. Based on the results obtained, the study outlined the consequences of land use change for flood events in the basin.

Institutional challenges in scaling-up climate change adaptation actions: experiences from rural communities in Senegal and Kenya

Regional institutions in Africa have the potential to reinforce the adaptive capacity of rural communities in handling climate change impacts. The institutional arrangements provide the rationale for scaling-up adaptation actions by setting the roles of individual players involved in the planning process at local, national and regional levels. The scaling-up then seeks to extend and disseminate the lessons learnt across the levels to support refinement and inclusive implementation of long-term climate change adaptation strategies. This article discusses these considerations through studies of two rural communities faced with the implementation of climate change adaptation strategies in Senegal and Kenya. The cases illustrate different approaches of institutional arrangements and scaling-up of adaptation actions from community to national levels. The lessons from the communities are typical of most vulnerable rural regions and were hence important for extended dissemination considering that the impacts of climate change in Africa are felt largely at community levels. A reduction of this vulnerability requires efficient and realistic adaptation strategies that seek to understand the rural communities while developing considerate policy-based alternatives at all levels of administration.