Intangible Flood Damage Quantification

Flooding is a natural disaster that may cause tremendous tangibleand intangible damage to the national economy. The tangible damage assessment, i.e. the monetary value of all direct and indirect physical damages, has already been studied, whileintangible damages have not yet been taken into account. Thisarticle, therefore, is the first systematic attempt to assess bothtangible and intangible damages. The new proposed Anxiety-Productivity and Income Interrelationgship Approach (API) has been developed to quantify the intangible damage in monetary terms. The Bangkok area has been selected as the research area because several severe flood events have occurredthere over the last two decades. The 1983 Bangkok flood caused 6600 million baht in damage, according to estimates by the National Statistical Office (NSO). This article examines the totalflood damage (including the intangible damage) at different flood magnitudes. Case studies with and without flood mitigation projects are studied and compared. Furthermore, thisarticle also discusses the improvements over the conventional approach offered by the new API methodology.     

Estimation of flood damage cost for Bangkok

Bangkok, located on a low lying alluvial deposit, is flooded almost every year by tide, river flow, and direct precipitation. Due to land subsidence caused by pumping of groundwater, the flooding is now more severe and more frequent than ever before. Various proposals have been presented to alleviate the flooding; however, selection of these alternatives would require cost-benefit analysis. The objective of this research is to estimate the cost of flood damage by first estimating the flood damage cost function in terms of depth and duration using the multiple regression analysis technique. In the case of Bangkok, results indicate that flood depth and flood duration are significant factors explaining flood damage in the residential and industrial areas. On the other hand, only flood depth was found to be an important factor affecting damage to the commercial and agricultural areas. The estimated cost functions served as a useful aid in the systematic computation of flood damage for 1983 which amounted to over 7.8 billion baht (US$ 1.00 baht 25.5).     

Implications of effluent discharge from a proposed wastewater treatment plant on coastal water quality in the upper gulf of Thailand

Abstract

The paper deals with the assessment of the change in coastal water quality due to effluent discharge from a wastewater treatment plant through an outfall in the Upper Gulf of Thailand. A hydrodynamic and water quality modeling approach is used to predict the water quality level in the vicinity of the outfall when the effluent discharge and concentration levels are specified. With the continuation of effluent discharge for a one‐year period, the concentration levels of coliform bacteria and nutrients increase significantly in the vicinity of the outfall. These inferred states of seawater quality would pose hygiene risks for green mussel cultivation and affect the ecosystem due to high nutrient enrichment and eutrophication. Recommendations for improvement are put forward keeping a balance between social, economic, and engineering considerations.