Restoration of Koggala lagoon： Modelling approach in evaluating lagoon water budget and flow characteristics

Groyne system modification is described related to restoration e orts to Koggala lagoon, Sri Lanka.The large-scale unplanned sand removal at the lagoon mouth shifted the formation of sand bar towards the lagoon and made adverse e ects on its ecosystem. After the removal of the natural sand bar, groyne system was constructed to avoid sand deposition in the lagoon and to protect the highway bridge (across the lagoon outlet channel) from the wave attack. The existing groyne system resulted the lagoon mouth being permanently open to sea which in turn led to many environmental problems. Groyne system modification is proposed in this study to reduce the sea water intrusion.Water budget and two-dimensional depth averaged hydrodynamic model were developed for understanding the hydrologic and flow characteristics of the lagoon. Numerical experiments was performed at lagoon mouth area for two cases: (1) existing condition and (2) proposed rubble mound groyne system condition. Comparison of results was obtained for both cases to describe flow pattern at lagoon mouth. Results further showed, the width should be reduced to a maximum of 40 m. Proposed mouth width (40 m) pushed the salting factor towards 0.5 from 0.68. Salting factor reduction with the groyne modification may result a predominant influence of fresh water which may in turn lead lagoon to a fresh water ecosystem.     

Ti/RuO_2-Pt电极电化学降解苯酚废水研究

研究以典型的难降解有机污染物苯酚为对象,用Ti/RuO2-Pt阳极进行电催化氧化降解研究,讨论了电解质、苯酚初始浓度、电流密度以及氨氮对苯酚降解效果的影响。研究结果表明:以NaCl为电解质比Na2SO4为电解质时处理苯酚的效果明显,而且电流密度越大、NaCl的添加量越多,苯酚全部降解所需的时间越短;在10mA/cm2的电流密度,0.3g/L氯化钠的添加量下,将苯酚从8mg/L降解为0需要30min。在电流浓度10mA/cm2,氯化钠添加量1.0g/L下,苯酚由20、40、80mg/L降解为0分别需要30、60、130min,降解时间随着浓度的增加呈接近正比增加;氨氮的存在不影响苯酚的电化学降解,而且苯酚优先降解,然后氨氮降解。     

Sex pheromone components of pyralid moths Terastia subjectalis and Agathodes ostentalis feeding on the coral tree, Erithrina variegata: Two sympatric species share common components in different ratios

Summary. Two common components, identified as (E)-11-hexadecenal (E11-16:Ald) and (E,E)-10,12-hexadecadienal (E10E12-16:Ald), were found in the extract of virgin females of two sympatric pyralid moths, Terastia subjectalis Lederer, and Agathodes ostentalis (Geyer). The amount of E11-16:Ald and E10E12-16:Ald was 0.12 and 2.8 ng/female for T. subjectalis and 2.0 and 1.8 ng/female for A. ostentalis, respectively. Hexadecanal (16:Ald) was also found at 0.7 ng/female in the extract of A. ostentalis, but EAG activity was unclear. In the field, T. subjectalis and A. ostentalis males were captured with species specific blends in the proportions of 5:95 and 50:50 blends. Blends attractive to one species did not attract the opposite one. Rubber septa loaded with 1 mg each of 5:95 and 50:50 blends of E11-16:Ald and E10E12-16:Ald were as attractive as two virgin females of T. subjectalis and A. ostentalis , respectively. This demonstrated that different ratios of shared pheromone components could provide species specific cues for critical mate location in the two sympatric pyralid moths. It is suggested that directional selection probably occurs in the pheromone blends in opposite directions in both species.     

Mainstreaming climate change adaptation in least developed countries in South and Southeast Asia

This paper undertakes an in-depth analysis of six least developed countries (LDCs) in South and Southeast Asia to assess the extent of mainstreaming climate change adaptation into national development plans by reviewing their National Adaptation Programmes of Action (NAPAs), national development plans, and Strategic Programs for Climate Resilience (SPCRs) (where available). The paper proposes two perspectives to analyze the level of mainstreaming and five factors that may affect such a level. The results show that there is a significant difference in the success of their mainstreaming efforts: mainstreaming is relatively advanced in Bangladesh, limited in Lao People’s Democratic Republic, the Maldives, and Nepal, and still minimal in Bhutan and Cambodia. Among the factors, the study finds that the inter-ministerial coordination supported by the highest levels of government is most relevant to the success of mainstreaming, which is measured by the integration of climate adaptation consideration into development priorities and a country’s own initiatives, particularly those involving budget allocation. Recognition of the need for mainstreaming and monitoring and evaluation also affect the success of mainstreaming efforts in LDCs. Another important factor is to make adaptation plans compatible with national development plans in terms of their time horizon, and SPCRs effectively facilitate this process. As all countries still require external support for advancing mainstreaming, the role of development partners is instrumental. The paper points to issues that need to be incorporated in the relevant NAPAs including updating to facilitate mainstreaming.     

Impact of rubble mound groyne structural interventions in restoration of Koggala lagoon,Sri Lanka; numerical modelling approach

Physical processes of the lagoon are influenced by structural interventions. Understanding the complex reality of physical processes sometimes difficult with field observations thus a model provides a simplified abstract view. Two dimensional hydrodynamic model is used to describe, restoration efforts to Koggala lagoon, a combined freshwater and estuarine complex of rich ecosystem on the southern coast of Sri Lanka. The lagoon mouth was naturally closed by a sand bar which controlled the seawater intrusion. Due to large-scale sand removal at lagoon mouth, formation of the sandbar shifted towards the lagoon. After the removal of natural sand barrier, rubble mound groyne structures were built to avoid sand deposition in the lagoon and to protect the highway bridge from the sea wave attack. Construction of the groyne resulted in the lagoon mouth being permanently open which in turn led to many environmental problems with saline intrusion. The aim of this study is to evaluate the current situation of the lagoon and propose alternative structural interventions for minimization of seawater intrusion and subsequently improve lagoon ecosystem. Hydrological parameters were investigated and mathematical models for hydrodynamic behavior of the lagoon were applied in order to describe the lagoon physical processes and flow characteristics. Existing rubble mound structures were redesigned in order to minimize the seawater intrusion. Numerical simulations were carried out for two different mouth widths (40 m and 20 m) with appropriate structural interventions. Existing salting factor for the lagoon is 0.68 and numerical simulation results showed salting factor for 40 m and 20 m openings are 0.61 and 0.54 respectively. This shows the mouth width can be reduced up to 20 m in order to obtain a slating factor close to 0.5, which indicates the predominant influence of fresh water which in turn leads lagoon to a fresh water ecosystem.