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|An Environmental Impact Study of Paddy Cultivation within Katagamuwa Sanctuary|
M. Wijeratne1, G. Amarasinghe2, A. Wickramaratne1
The proposed project, 32.5 ha of arable land for paddy cultivation is within the Katagamuwa sanctuary and very close to the Katagamuwa tank. Katagamuwa was declared a sanctuary in 1938, and covers an area of 1000 ha. The forest with large dry-zone flora occupies the surrounding area, but the specific location is covered by grasses, climbers, bushes and shrubs with a flat terrain. The Katagamuwa sanctuary is confined to Hambantota district and Divisional Secretary Division of Tissamaharamaya. The proposed project involved agricultural activities reserved for paddy cultivation during the two major growing seasons, yala and maha. It is expected to cultivate rice under rainfed condition, and irrigation facilities will be obtained from the nearby tank. The observation revealed that paddy cultivation has been undertaken up to the recent past and the remains are still visualized. The objective of this study is to identify the feasibility of paddy cultivation within the sanctuary.
An Initial Environmental Examination (IEE) has been conducted during May-July 2005. Preliminary information with regard to the project was extracted from the project proposal and undertaking series of informal discussions. Further, relevant documents were reviewed to understand the past and present states of the project location. The IEE team paid several visits to the location and utilized Rapid Rural Appraisal (RRA) techniques to extract the information. Hence, the findings are based on verifiable evidence.
The location is part of an ancient village that is surrounded by forest, and no human settlement can be seen. Further, surrounding area does not provide income-generating activities in the context of agriculture. However, few privately maintained tourist restaurant are functioning with some tourist activities. At present, there is no conflict with animals as the human activities are very limited, the abandoned paddy field is also enjoyed by wildlife. However, with the project implementation, this situation will be changed, and in order to protect the cultivation some measures have to be taken. Even though there are very valuable natural products, people do not collect them for economic means. As the proposed project location is within the Katagamuwa sanctuary, intended paddy cultivation may affect the wildlife, especially the fauna as it is connected to the major water source, the Katagamuwa tank. The observations imply that the animal pass through the proposed land to reach the tank. This might be the most important adverse effect on environment for which mitigatory measures are warranted. Further, use of heavy machinery during there construction period of the tank bund also may disturb the eco-system. Pertaining to paddy cultivation, tractors and other agricultural equipment have to be used. Such activities too, may have an impact on the eco-system. The Katagamuwa sanctuary is an entry point to Yala national park. Therefore, activities of the proposed project might cause an indirect impact on the eco-system of Yala. However, no adverse situation can be expected for the economic and social life of the people around the area. There are, in fact, negative impacts on the environment but provision should be granted to development activities enforcing mitigatory measures for conservation. Further, on policy framework, execution of human activities can be allowed without making drastic negative consequences.
Impact of Climate Change on Cropping Calendar of Field Crops:
A Case Study in Home Gardens in Southern Sri Lanka
C.M. Navaratne1, K.D.N.Weerasinghe1
A research was conducted to identify the change of cropping calendar with climate variation in field crops grown in home gardens of southern Sri Lanka. The climatic water balance approach and the rainfall probability concepts were used for the study. The changes of onset, duration, magnitude and risk of rainfall were assessed using the daily rainfall data for 50 consecutive years (1950 ~ 2000) from 5 stations in different agro-climatic regions and available pan evaporation data.
The changes of onset, magnitude and duration of rainfall were assessed by means of 3-year moving averages curves and linear trend lines. The risk was determined considering the number of dry weeks per cropping season. The limits of 10 mm weekly rain at 75% probability and Hargreave’s Moisture Availability Index at 0.34 in weekly basis were used to demarcate dry weeks and wet weeks of the area. At least the beginning of three consecutive wet weeks was taken into account to identify the onset of rain and the commencement of crops in both Yala and Maha seasons. The current cropping calendar of field crops grown in home gardens was established through a farmer survey.
The results revealed that the onset of rain in Yala and Maha seasons is vulnerable and delaying with time. This leads to delay of the crop commencement time as well.
The establishment of crops by farmers in Yala falls between 11th and 18th week depending on the location. In some locations, there is no closer correlation between onset of rain and crop commencement. In all locations, crop commencement for Maha falls on 38th – 41st week that is earlier than the rainfall onset.
The number of dry weeks per cropping season and the maximum length of dry period are increasing whereas the annual rainfall and maximum length of wet period are decreasing in all regions with time.
Therefore, it is clear that the cropping calendar of annual crops with the onset, amount, duration and risk of rainfall have been changed with climate variation. If the farmer adjusts his annual crop commencement week to tally with the week of rainfall onset, the cropping calendar would coincide with the rainy period, which may reduce the water scarcity problems that may occur during the cropping season.
The results of the research helped to identify the climate change in the area in respect to onset, magnitude and risk of rainfall and produced the regional maps to illustrate the above changes.