Climate Change Impacts on Rice Farming Systems in Northwestern Sri Lanka

Sri Lanka has achieved tremendous progress since 1950 in crop production and food availability. Yields grew at an impressive rate until leveling off in the mid-eighties. Sri Lanka's population is anticipated to grow in the coming decades, creating an ever-greater demand for food security on the household, sub-district, regional, and national scales.The agricultural sector in Sri Lanka is vulnerable to climate shocks. An unusual succession of droughts and floods from 2008 to 2014 has led to both booms and busts in agricultural production, which were reflected in food prices. In both instances, the majority of farmers and consumers were adversely affected.At present the rice-farming systems are under stress due to inadequate returns for the farmers and difficulty in coping with shocks due to climate, pests, and diseases, and prices for produce. There are government price-support mechanisms, fertilizer-subsidy schemes, and crop insurance schemes, but the levels of the supports are modest and often do not effectively reach the farmers

Role of human agency in the transformation of the biogeography of Sri Lanka

The area referred to as the ‘Central Highlands of Sri Lanka’, despite being the venue of a thin scatter of ‘Stone Age’ human settlements was sparsely populated by man throughout the island’s ‘Pre-Modern Era’, and much of it, especially at its higher elevations remaining under primeval forest cover. In late medieval times when this highland area became a part of the ‘Kandyan Kingdom’, its forest-clad localities, except those that were appurtenant to village settlement ecology, tended to be strictly protected under royal decree. The cultivation of coffee on large areas of land – ‘plantations’ or ‘estates’ –commenced as a major economic enterprise after the establishment of British rule over the island in the early 19th century. This invariably entailed the extensive clearing of forests. The ‘Ferguson map’ that depicts the coffee estates that existed in 1863 and 1880 provides valuable information about the distribution of coffee plantations. The present study is a product of an attempt to determine the location and the extent of coffee plantations in relation to vegetation zones, administrative districts, and river basins of the Central Highlands. It indicates, inter alia, the main plantation area in the Upper Mahaveli catchment, and in the sub-montane zone. The second largest extent was in the Kelani Basin. Clearing of forests led to erosion of hillslopes, siltation of riverbeds and the low-lying areas, particularly in these two river basins. Within a period of 50 years the landscape of a large part of the Central Highlands was transformed from forest-covered hills to a landscape dominated by plantations. This process caused irreparable damage to the biodiversity of the montane and sub-montane areas of Sri Lanka.Keywords: endemism, evolutionary stable unit, mammal subspecies, habitat quality, ecological niche, mammalian evolution

A comparative study of elevation data from different sources for mapping the coastal inlets and their catchment boundaries

Mapping coastal inlets and their catchment areas is essential for management of the coastal zone. The coastal inlets are important channels of exchange of nutrients, water and sediment between the land and sea. They are also important elements of the coastal hydrological system and play a vital role in controlling the water flow into the sea during floods. Blocking of the coastal inlets is one of the main causes of flooding in the lower reaches of the major rivers in Sri Lanka. Delineation of the boundaries of inlet catchments is essential for modelling the inlet processes and this is normally done using elevation data. The traditional sources of elevation data are the topographic maps. In Sri Lanka, detailed topographic maps (1:10,000) are available only for a limited area, and the rest of the country is covered by 1:50,000 and 1:63,360 maps. The low resolution maps are not sufficiently detailed in areas of low relief, such as the coastal lowlands. As a result, the catchment boundaries based on these data sources are not accurate enough for inlet studies. Two alternative sources of elevation data that can be used for this type of studies are the shuttle radar topography mission (SRTM) global data set and light detection and ranging (LiDAR) data (5 m) available for a limited area of the coastal belt. This study compares the traditional map data for the Galle district with the SRTM digital elevation models (DEM) at 30 m and 90 m resolutions and LiDAR DEMs. At first, the DEMs derived from all data sources were compared using the cross-sectional profiles. Secondly, a comparison was made using the spot heights obtained from 1:10,000 maps with the corresponding heights from the SRTM 30 m DEM. The 1:10,000 scale agricultural based mapping project (ABMP) (10 k ABMP) was used as the reference data set and all other data products were compared with that. The analysis of the data revealed that the LiDAR data set has the best match with the 10 k ABMP dataset. The SRTM 30 m DEM showed a high level of correlation with 10k ABM P maps at the high elevations, but the match at the low elevations was less as indicated by the low R-2 values. However, the SRTM data is marginally better than the 50 k ABMP in the coastal area. This suggests that SRTM 30 m data set is the best data set available for the delineation of inlet boundaries in the coastal areas