Vannak Ann

In the Lower Mekong Basin, paddy fields often appear as mosaics, with soil mounds covered by trees or other plants in a spotty distribution. These soil mounds are commonly named termite ‘lenticular mounds’ because termite bioturbation is considered to be at their origin. Termite mounds host a large diversity of animals and plants, increasing landscape patchiness. Because the preservation of these islands of biodiversity is threatened by modern agricultural practices, the aim of this study was to quantify their abundance and the services they provide to the local population. The abundance of mounds and their use by the population were quantified in a catchment in Cambodia. We found that mounds density reached ~2 mounds ha−1. Interviews carried out within the catchment showed that most of the interviewees used mounds for increasing the fertility of their field and for the cultivation of rice and other plants (e.g. sponge gourd and pumpkin). In addition to their potential to increase p...

This dataset comes from a survey carried out in Chrey Back long term observatory (Cambodia). 61 persons from 13 villages located in Chrey Back watershed were interviewed in order to understand the local perception of the utilization of termite mounds. The dataset describes the questions and responses of villagers in differentiating the soil type (Arenosol vs. Acrisol) and position within the watershed (lower land (LL) vs. upper land (UL)). Survey_detail.csv describes the number of responses per village in Chrey Back catchement according to their positions in the watershed (LL: Lower land vs. UL: Upper land) and soil types (Acrisol vs. Arenosol). Questionnaire.csv describes the percentage of positive and negative answers from a total of 17 and 14 responses in the Arenosol, in LL and UL respectively, and 15 responses in both LL and UL in the Acrisol. Open_answers.csv details the comments and replies of villagers.

The urban infrastructure, particularly water supply and drainage systems, have deteriorated severely in the past two decades in Phnom Penh, the capital city and the economic center of Cambodia. Water pollution caused by untreated wastewater is one of the serious problems that confront most developing countries (Kwai et al.1991). In Phnom Penh City, all kinds of wastewater are discharged to rivers, lakes and wetlands throughout the city without proper treatment causing serious surface water pollution. Water testing is an essential factor to control water pollution. However, water quality data and water quality testing systems are still poorly developed in Cambodia due to lack of facilities and technical expertise. Therefore, there is no information available on sewage water quality in Phnom Penh City. That’s why the work is aimed at collating basic information about the situation of water supply, waste water system and solid waste. The present information will provide the basis for targeting further field research. This is included the overview of sources and activities that may lead to pollution, with an appreciation of type of water pollutants involved, their magnitude and movement. Types of waste and effluent disposal including sanitation, liquid and solid waste management systems are described. After reviewing all the available, we found that the distribution of water has been well organized by the Phnom Penh Water Supply Authority while the managements of the wastewater, storm water and solid waste are poor due to the rapid urbanisation and industrialisation.Peer reviewe

Dataset describing sheeting properties made by termites (names, and feeding and building categories are given) sampled in 34 study sites, including M-Tropics observatories, from 19 countries. Data coming from 15 published studies are also given, for a total of 49 sites and 21 countries. The dataset include the locations (site names, countries, GPS coordinates, mean annual precipitations 'MAP') and soil properties (electrical conductivity in µS cm-1, pH, C content in %, soil aggregate stability (in % aggregates > 200 µm) and sand, silt and clay contents in %) of termite sheetings and the surrounding topsoil. The Response ratio (R = Value of termite sheeting / Value oft he bulk soil) is also given for each variable. Files include the whole dataset (n = 249 observations) and the average per species and study site (n = 84 observations).

River sediments are composed by a variety of grain sizes which determine their permeability and biogeochemistry. The aim of this thesis was to test whether differences in river sediment physical characteristics generate differences in biofilm biomass and metabolic activity in a Mediterranean river. To this aim, formulae for estimating hydraulic conductivity were reviewed, and the relationship between sediment grain-size distribution and microbial biomass, and microbial metabolism depth gradients were analyzed. Results suggest selecting the Kozany-Carman formula to estimate hydraulic conductivity for Tordera sandy sediments. Sediment physical properties affected accumulation of organic matter, chlorophyll-a and bacteria but this effect was different depending on hydrological events and microbial group considered; bacteria being the most affected. Microbial activities in sediment depth were regulated by the permeability of streambeds through organic compounds contributing to microbial...

Tonle Sap Lake (TSL) in Cambodia is the largest shallow lake in Southeast Asia. Influenced by flood pulse system of the Mekong River, TSL provides diverse benefits including ecosystem services, ecological functioning, and flood water storage in the floodplains. However, extreme events (e.g., flooding) due to rising water level caused by dam break and/or heavy rainfall in the Mekong River Basin could threaten the ecosystems of the lake, community health and economic growth in the region. Flood mapping under such extreme event could be informative in the flood risk and emergency management. In this study, we aim to develop a flood risk boundary map in TSL using an existing 2D hydrodynamic model (Caesar-Lisflood, CL) with rising water levels estimated by Gumbel distribution. As a result, the extreme water level of 1% chance (or 100-year flood return period) exceeding the annual maximum water level at Prek Kdam station was approximately 11.38 m resulting in the largest inundation area o...