Biodiversity Assessment of Paddy Field Ecosystem using Birds as a Biodiversity Indicator

Biodiversity assessment is considered in making decisions concerning declaration ofprotected areas, management of nature reserves and assessment of the success ofmanagement decisions within a particular area. Biodiversity indicators are used as measuresof biodiversity. Degree of disturbance or fragmentation of a definite habitat can be measuredusing specific indicator species. A variety of invertebrates and vertebrates are widely used asindicators of biodiversity. Birds are one of the best species for the national and internationalbiodiversity schemes to be used as a biodiversity indicator.This study focused on the use of birds as an ecological indicator to assess the paddy fieldecosystem. The study was carried out in a minor irrigation system in Awlegama AgrarianService area in Wariyapola Divisional Secretariat. Bayawa was the selected tank with nearlya 38 ha of command area. A standard fixed-radius point count method with the radius set at25 m was used to sample birds in the paddy field ecosystem. Shanon index was used toexplain the results. During a single rice cycle, rice plants undergo three main phenologicalstages namely; vegetative, reproductive and ripening. All these stages are influenced byfarming practices such as tillage, irrigation, crop establishment, agrochemical application andweeding. Different stages with different farming practices create distinct habitats for variousbird species. According to the results, the highest Shanon index value (highest diversity) wasrecorded during the vegetative stage. Birds‟ diversity had a significant, strong (p=0.05)negative correlation with the age of the paddy. Initial land preparation and vegetative stagesprovide more food sources for the predatory birds who feed on worms, insects and snails;some of whom act as pests of paddy. Mixing of upper and the sub-soil layers in landpreparation stages supply more feed for predatory birds. Cattle Egret, Red Wattled Lapwing,Intermediate Egrets, Indian Pond Heron, Black Necked Stroke were in abundance at landpreparation and vegetative stage. Yellow crowned woodpecker and White throated muniawere recorded during the later stages. A variety of management practices such as landpreparation, crop establishments, irrigation, nutrient and pest management, harvesting withinthe paddy field facilitate to create different habitats with different eco systems and suitablefood for bird species. The birds as a biodiversity indicator, symbolise the ecosystem and itreflects the existing condition of an ecosystems. A detailed study will reveal how these birdswould help to manage different pests in the paddy fields to bring benefits to the farmers.Keywords: Biodiversity indicator, Ecosystem, Paddy field, Birds, Cattle Egre

Runoff Prediction in an Ungauged Catchment of Upper Deduru Oya Basin, Sri Lanka: A Comparison of HEC-HMS and WEAP Models

Runoff prediction from ungauged catchment has always been a challenging task, requires transfer of hydrologic information from gauged to ungauged catchments. However, it is not clear whether information transfer among nearby catchments is suitable across a wide range of climatic and geographic regions. In this study, stream flow data of a gauged catchment (Tittawella tank) were used for calibration and validation of HEC-HMS (Hydrological model) and WEAP (Water resource model). Watershed area ratio technique was adopted to simulate runoff from an ungauged catchment (Hakwatuna Oya) and the results were compared. The simulated flows generated by both models in calibration and validation showed good agreement with observed flows. Monthly flows simulated by both models were quite similar. Although HEC-HMS enables runoff simulation on daily basis with better prediction of peaks, necessary for flood forecasting, monthly simulation is adequate for water managers to take management decisions. Therefore, WEAP as a single model can be used for both runoff simulation and taking management decisions in Hakwatuna Oya catchment

Spatially distributed hydrological modeling of Upper Uma Oya Catchment using soil and water assessment tool SWAT

In De Silva, R. P. (Ed.). Sweden International Training Course on Remote Sensing Education for Educators, Decadal Proceedings 1990-2004: a collection of selected papers submitted by former participants. Peradeniya, Sri Lanka: Geo Informatics Society of Sri Lanka (GISSL

Water Pollution in a Natural Stream and Its Impacts on Society and Environment: A Review of Studies on Meda Ela, Sri Lanka

Abstract: Meda Ela which originates from Kandy Lake and runs through Kandy city is considered to be one of most polluted tributaries of Mahaweli River. The objective of the study was to critically review the published research findings related to Meda Ela pollution to existing problems, research gaps and the means to rectify the situation. The review was carried out under the categories of socio-economic background, land use changes, sources of pollution, solid and waste water disposal, water quality, cost due to water pollution, economic benefits and major stakeholders and their interactions of Meda Ela. Study identified a very high urbanization rate in the watershed during the last decade compared to previous 30 years. Major point sources include the hospital, bus stand, railway station, central market and the residences on either side of Meda Ela. According to the literature, elevated pollution levels are reported during wet season and NO- 3, NH+ 4, PO3- 4, suspended solids, heavy metals, DO, BOD and COD showed above threshold limits. This is an indication of non-point source pollution which is responsive to hydrological conditions. Impacts of water pollution include vector borne diseases such as Dengu and Chickengunya, bad odour, flash floods and contamination of shallow groundwater with heavy metals. The social and management setup in the watershed is very complex since many stakeholders are involved in polluting and managing Meda Ela. The analysis revealed that the relationship among different stakeholders is highly diverse and as a result, their contribution to control water pollution in Meda Ela is also very different. Hence, a strong connection should be established between community and other stakeholders to develop an efficient and effective management plan to safeguard Meda Ela stream and its watershed