scholarly journals APPLICATION OF BIAS-CORRECTION AND DOWNSCALING METHOD TO KALU GANGA BASIN IN SRI LANKA

Author(s):  
Cho Thanda NYUNT ◽  
Hiroki YAMAMOTO ◽  
Akio YAMAMOTO ◽  
Toshihoro NEMOTO ◽  
Masaru KITSUREGAWA ◽  
...  
2016 ◽  
Author(s):  
Cho Thanda Nyunt ◽  
Toshio Koike ◽  
Akio Yamamoto

Abstract. We introduce a 3-step statistical bias correction method to solve global climate model (GCM) bias by determining regional variability through multi-model selection. This is a generalized method to assess imperfect GCMs that are unable to simulate distinct regional climate characteristics, either spatially or temporally. More remaining local bias is eliminated using an all-inclusive statistical bias correction addressing the major shortcomings of GCM precipitation. First, the multi-GCM choice is determined according to spatial correlation (Scorr) and root mean square error (RMSE) of regional and mesoscale climate variation in a comparison with global references. After multi-GCM selection, there are three major steps in the proposed bias correction, i.e., the generalized Pareto distribution (GPD) for extreme rainfall bias correction, ranking order statistics for wet and dry day frequency errors, and a two-parameter gamma distribution for monthly normal rainfall bias correction. Best-fit GPD parameters are resolved by the RMSE, a Hill plot, and mean excess function. The capability of the method is examined by application to four catchments in diverse climate regions. These are the Kalu Ganga (Sri Lanka), Pampanga, Angat and Kaliwa (Philippines), Yoshino (Japan), and Medjerda (Tunisia). The assumption of GCM stationary error in the future is verified by calibration in 1981–2000 and validation over 1961–1980 at two observation sites. The results show a favorable outcome. Overall performance of catchments was good for bias-corrected extreme events and inter-seasonal climatology, compared with observations. However, the suggested method has no intermediate grid scale between the GCM grid and observation points, and requires a well-distributed observed rain gauge network to reproduce a reasonable rainfall distribution over a target basin. The results of holistic bias correction provide reliable, quantitative and qualitative information for basin or national scale integrated water resource management.


2015 ◽  
Vol 21 ◽  
pp. 114-115
Author(s):  
Kavinga Gunawardane ◽  
Noel Somasundaram ◽  
Neil Thalagala ◽  
Pubudu Chulasiri ◽  
Sudath Fernando

Crisis ◽  
2010 ◽  
Vol 31 (1) ◽  
pp. 30-35 ◽  
Author(s):  
Sudath Samaraweera ◽  
Athula Sumathipala ◽  
Sisira Siribaddana ◽  
S. Sivayogan ◽  
Dinesh Bhugra

Background: Suicidal ideation can often lead to suicide attempts and completed suicide. Studies have shown that Sri Lanka has one of the highest rates of suicide in the world but so far no studies have looked at prevalence of suicidal ideation in a general population in Sri Lanka. Aims: We wanted to determine the prevalence of suicidal ideation by randomly selecting six Divisional Secretariats (Dss) out of 17 in one district. This district is known to have higher than national average rates of suicide. Methods: 808 participants were interviewed using Sinhala versions of GHQ-30 and Beck’s Scale for Suicidal Ideation. Of these, 387 (48%) were males, and 421 (52%) were female. Results: On Beck’s Scale for Suicidal Ideation, 29 individuals (4%) had active suicidal ideation and 23 (3%) had passive suicidal ideation. The active suicidal ideators were young, physically ill and had higher levels of helplessness and hopelessness. Conclusions: The prevalence of suicidal ideation in Sri Lanka is lower than reported from the West and yet suicide rates are higher. Further work must explore cultural and religious factors.


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