Water Quality of the Mun River in Thailand—Spatiotemporal Variations and Potential Causes

Abstract

The water quality of the Mun River, one of the largest tributaries of the Mekong River and an important agricultural area in Thailand, is investigated to determine its status, identify spatiotemporal variations and distinguish the potential causes. Water quality dataset based on monitoring in the last two decades (1997–2017) from 21 monitoring sites distributed across the basin were analyzed using seasonal Kendall test and water quality index (WQI) method. The Kendall test shows significant declines in fecal coliform bacteria (FCB) and ammonia (NH3) in the upper reaches and increases in nitrate (NO3) and NH3 in the lower reaches. Strong temporal and spatial fluctuations were observed in both the concentrations of individual parameters and the WQI values. Seasonal variation of water quality was observed at each monitoring site. WQI values in August (flood season) were generally among the lowest, compared to other seasons. Spatially, sites in the upper reaches generally having lower WQI values than those in the lower reaches. Excessive phosphorus is the primary cause of water quality degradation in the upper reaches, while nitrogen is the primary parameter for water quality degradation in the lower reaches. Urban built-up land is an important “source” of water pollutants in the lower basin, while agricultural land plays a dual role, affecting across the basin.

Evaluación de la calidad de aguas superficiales en espacios recreacionales, una propuesta integradora de marcadores químicos y microbiológicos

“…El agua es un recurso frágil que puede modificarse ante la presencia de cambios climáticos o la actividad humana (1). El cambio climático afecta la cantidad de agua por aumento o disminución de las precipitaciones, acontecimientos climáticos extremos, cambios estacionales de las épocas de precipitaciones y variaciones térmicas (2). Asimismo, aumenta el riesgo de la presencia de microorganismos y algas tóxicas; todo lo cual incide en los sistemas que utilizan el agua como recurso.…”

Calidad bacteriológica del agua de cuatro balnearios del municipio de Valledupar (Colombia)

“…En comparación con los estudios de Zhao et al, (2018) y Tian et al, (2019), afirman que la concentración de coliformes totales varía entre los muestreos realizados en las diferentes temporadas del año (secas y lluvia), haciendo notar que la presencia de coliformes está en función del aporte de sedimentos de los terrenos aledaños al cuerpo de agua lo que hace que la densidad del número de microorganismo aumente o disminuya.…”

Trends of Runoff Variation and Effects of Main Causal Factors in Mun River, Thailand During 1980–2018

“…Due to data availability, daily rainfall data at 9 meteorological stations (including Lam The Mun River basin has a tropical savanna climate which is most significantly affected by tropical monsoons in Asia [25]. The climate and hydrology within the basin show significant seasonal differences brought upon by the seasonal monsoons, forming distinct rainy (flooding) and dry seasons that last from June to October, and November to May of the following year, respectively [15]. Rainfall in the rainy season accounts for 92-98% of the total annual rainfall and only 2-8% in the dry season.…”

“…As the largest tributary of the Mekong River in Thailand, Mun River inputs about 20 × 10 9 m 3 of freshwater per year to the Mekong River on average [15]. This is important for ecosystems and people living in the middle and lower reaches of the Mekong River.…”