Comparing interpolation techniques for monthly rainfall mapping using multiple evaluation criteria and auxiliary data sources: A case study of Sri Lanka

Interpolating climatic variables such as rainfall is challenging due to the highly variable nature of meteorological processes, the effects of terrain and geography, and the difficulty in establishing a representative network of stations. While interpolation models are being adapted to include these effects, often the rainfall data contain significant gaps in coverage. In this paper, we evaluated rainfall data from an agro-ecological monitoring network for producing maps of total monthly rainfall in Sri Lanka. We compared four spatial interpolation techniques: inverse distance weighting, thin-plate splines, ordinary kriging, and Bayesian kriging. Error metrics were used to validate interpolations against independent data. Satellite data were used to assess the spatial pattern of rainfall. Results indicated that Bayesian kriging and splines performed best in low and high rainfall, respectively. Rainfall maps generated from the agro-ecological network were found to have accuracies consistent with previous studies in Sri Lanka.     

Limnology and culture-based fisheries in non-perennial reservoirs in Sri Lanka

This study was carried out to investigate the possibility of using the limnological characteristics of non‐perennial reservoirs in Sri Lanka for the future management of culture‐based fisheries. Forty‐five reservoirs were randomly selected to study their limnology, out of which 32 were stocked with fish fingerlings of Chinese and Indian carps, tilapia and freshwater prawn at stocking densities ranging from 218–4372 fingerlings ha^?1. Of these, 23 reservoirs were harvested at the end of the culture period (6–10 months). Thirteen limnological parameters were measured during the water retention period of each of the 45 reservoirs between November 2001 and January 2004. The mean values of the limnological parameters were used to ordinate the reservoirs through principal component analysis. Ordination showed a productivity gradient among reservoirs where Secchi disc depth, total phosphorus, chlorophyll‐a, inorganic turbidity and organic turbidity were identified as key factors. The total fish yield of culture‐based fisheries was positively correlated to the scores of the first principal component axis. This study reveals that it is possible to classify non‐perennial reservoirs in Sri Lanka based on the above limnological parameters in order to develop culture‐based fisheries and that they could be applicable in comparable water bodies elsewhere in the tropics.     

Equity in bulk water allocation: the case of the Mahaweli Ganga Development Project in Sri Lanka

This article evaluates the equity performance of bulk water allocation as an irrigation management strategy in the Mahaweli Ganga Development Project, Sri Lanka. Through semi-structured interviews with farmers and irrigation officials, the study collected local perceptions using seven indicators: water rights; decision-making process; contribution of resources for irrigation maintenance; water allocation rules; actual water distribution; information sharing; and conflict resolution. The results highlight gaps in the institution such as the need to enhance the water rights of landless farmers, further encourage crop diversification, increase transparency in decision making, instil a risk-management approach, and strengthen accountability.     

Milk Coagulation Properties and Milk Protein Genetic Variants of Three Cattle Breeds/Types in Sri Lanka

Milk coagulation is the primary step in the development of most dairy products. Raw milk from individual cows and different breeds exhibit distinct coagulation capacities. This variation is largely influenced by milk protein genetic variants. The aim of the present study was to evaluate differences in coagulation properties between milk obtained from three cattle breeds/types found in Sri Lanka. A total of 90 milk samples (400 mL from each individual) were collected from two Sri Lankan cattle breeds/types (Thamankaduwa White/TW and Local/“Batu” cattle) and one European cattle breed (Friesian). Collected samples were subjected to enzymatic coagulation using commercial rennet source (Chymax®, Christian Hansen Standard, Denmark) and lactic acid bacteria (LAB) coagulation using a commercial starter culture(YFL 8 12,Christian Hansen Standard, Denmark) to determine milk coagulation properties. Different properties of milk coagulum such as yield, curd firmness, syneresis and rheological properties were evaluated. The biochemical composition (lactose, protein, fat, solid-non-fat) of milk samples were determined. Capillary Zone Electrophoresis (CZE) method was used to determine milk protein genetic variants. Experimental design was Nested Completely Randomized Design with three treatments. Milk coagulation time and curd firmness after enzymatic-coagulation were not significantly different (p>0.05) among the breeds. Coagulum yield was significantly higher (p<0.05) for the TW type than that of other breeds. Coagulum yield was negatively correlated with β-caseinA1 and α-lactalbumin in both enzymatic (-0.58) and LAB coagulation (-0.69). Coagulum yield was positively correlated (p<0.05) with β-casein B variant (0.70), protein (0.34) and lactose (0.36) contents. Meltability value was weakly and positively (p<0.05) correlated (0.34) with fat content of milk. Overall results indicate that there is a significant correlation between milk coagulation properties and milk protein genetic variants in three cattle breeds/types considered in the current study. TW type is the unique among studied breeds in terms of coagulation properties and milk protein genetic variants.     

Valuing the Cultural Landscapes Past and Present: Tea Plantations in Sri Lanka

Abstract

The study focuses on tea plantation cultural landscapes in Sri Lanka and its historical formation, present issues and future considerations. [Sri Lanka was known as Ceylon before 1972. At present, the country uses Sri Lanka for all related documents.] According to the research, the tea estate is identified as the main building unit of tea heritage. This paper reveals the historical formation of tea heritage and its contribution to the existing landscape. This study focuses on the Nuwara Eliya region, as it is the main area for tea cultivation. The present condition of tea plantations in Sri Lanka is derived through a survey conducted in Labookellie estate, Blue Field estate and Pedro estate. Past and the present circumstances are examined through analysis of literature, topographical maps and site observations, while interviews with outsiders (foreign visitors) were used to strengthen the thoughts on tea plantation landscapes. This paper reveals basic concepts such as agriculture as a heritage, active agriculture and value added through future conservation and development procedure. The paper first discusses the formation of tea estates and governing factors. Second, the paper explains estate settlement as the main building block of tea heritage with researched case studies and explains existing landscape values. Third, the paper explains future thoughts on the tea plantation landscapes in Sri Lanka. Opinions of foreign visitors to the plantation are considered as a valuable contribution to the conclusions. The paper stresses the importance of understanding tea estate cultural landscapes and their heritage value for future planning and the conservation priorities in Sri Lanka.     

乡土之路--杰佛里·巴瓦的风景园林设计探索之路解析

斯里兰卡著名建筑师与风景园林师杰佛里·巴瓦勇于探索建筑设计与风景园林设计的关系,其风景园林设计作品在国际风景园林界产生了很好的影响,有人称赞他为建筑与风景园林设计的结合,走出了成功的一步。他在经济并不发达、政治与民族关系纷繁复杂的斯里兰卡,默默无闻地执著工作,并最终获得成功,同时也得到世人的认可。巴瓦的才华是有目共睹的,他执著的精神和强烈的责任感,更加值得世人敬佩和学习。通过探讨他的设计理念和设计方法,试图从中找到其成功答案——如何走上乡土之路。     

Association between some planktonic species and physicochemical characteristics of the water of Loktak Lake,Manipur, India

Four‐hourly data were collected for 24 hour periods in the months of December (1977), April (1978), July (1978) and December (1978) in respect of some physicochemical characteristics and plankton population in a protected part of the Loktak Lake (Manipur) India. Highly significant correlations, positive as well as negative, were observed between the diurnal and seasonal variations of physicochemical characteristics with those of total phyto or zooplankton of certain species.     

Chemistry of tap water in Sri Lanka‐implications on health

A preliminary survey on the chemical quality of tap water in Sri Lanka has been carried out and has been grouped into three categories depending on the source of the water. It was revealed that in certain parts of Sri Lanka, the tap water does contain excess quantities of lead. The Piper trilinear diagram shows that much of the tap water of Sri Lanka belongs to the Ca#shMg‐HCO₃ type. Low pH values have also been observed in certain areas and could bring out excess dissolved ions into the tap water. In view of the fact, that only a small percentage of the population of Sri Lanka have access to piped water, no serious health hazards due to the poor quality of the tap water have been encountered.     

Gas Transport Parameters for Compacted Reddish-Brown Soil in Sri Lankan Landfill Final Cover

Gas exchange through the compacted final cover soil at landfill sites plays a vital role for emission, fate, and transport of toxic landfill gases. This study involved measuring the soil-gas diffusivity (Dp/Do, the ratio of gas diffusion coefficients in soil and free air) and air permeability (ka) for differently compacted soil samples (reddish-brown soil) from the final cover at the Maharagama landfill in Sri Lanka. The samples were prepared by either standard Proctor compaction or hand compaction to dry bulk densities of 1.60–1.94??g?cm-3. Existing and modified models for predicting Dp/Do and ka were tested against the measured data. The simple, single-parameter Buckingham model predicted measured Dp/Do values across compaction levels equally well or better than a dry bulk density (DBD) dependent model and a soil-water retention (SWR) dependent model. The measured ka values for differently compacted samples were highly affected by the compaction level and the sample moisture preparation method. Also, for air permeability, a single-parameter Buckingham-type ka model was most accurate in predicting ka in the differently compacted soil samples. Equivalent air-filled pore diameters (the effective diameter of the drained pores active in leading air through the sample) for gas flow, deq, were calculated from the measured Dp/D0 and ka values. The deq increased with compaction level, suggesting that a very high compaction level creates well-connected macropores in the reduced total pore space of the cover soil. This is an important consideration when designing cover soils for optimally low water and high oxygen exchange while minimizing climate and toxic gas emissions from the waste layer to the atmosphere.     

Effect of sodium metabisulphide on ethanol production in coconut inflorescence sap

The addition of up to 200 mg l^?1 of sodium metabisulphite to coconut inflorescence sap was found to suppress the non-ethanol producing micro-organisms and permit ethanol production by pure yeast cultures to different extents. At metabisulphite concentrations higher than 150 mg l^?1 the ethanol yields from sap fermented with a natural inoculum increased under laboratory conditions. In the field, introduction of sodium metabisulphite to sap collecting pots gave maximum ethanol yield at a concentration of 188 mg l^?1 and on fermenting for 36 days. A response function was derived, based on field observations, to predict the ethanol yields at different sodium metabisulphite concentrations up to 325 mg l^?1 and durations of fermentation 1 to 5 days.