Effects of lockdown due to COVID-19 outbreak on air quality and anthropogenic heat in an industrial belt of India.

Highly urbanized and industrialized Asansol Durgapur industrial belt of Eastern India is characterized by severe heat island effect and high pollution level leading to human discomfort and even health problems. However, COVID-19 persuaded lockdown emergency in India led to shut-down of the industries, traffic system, and day-to-day normal work and expectedly caused changes in air quality and weather. The present work intended to examine the impact of lockdown on air quality, land surface temperature (LST), and anthropogenic heat flux (AHF) of Asansol Durgapur industrial belt. Satellite images and daily data of the Central Pollution Control Board (CPCB) were used for analyzing the spatial scale and numerical change of air quality from pre to amid lockdown conditions in the study region. Results exhibited that, in consequence of lockdown, LST reduced by 4.02 °C, PM10 level decreased from 102 to 18 µg/m3 and AHF declined from 116 to 40W/m2 during lockdown period. Qualitative upgradation of air quality index (AQI) from poor to very poor state to moderate to satisfactory state was observed during lockdown period. To regulate air quality and climate change, many steps were taken at global and regional scales, but no fruitful outcome was received yet. Such lockdown (temporarily) is against economic growth, but it showed some healing effect of air quality standard.

Inundation dynamics of the natural and manmade wetlands in the Mayurakshi River basin, Eastern India.

The present study aimed to measure wetland inundation inconsistency level (IIL) at a spatial scale to appraise the potential serviceability in the Mayurakshi river basin of Eastern India. Inconsistency was used for measuring both wetland water presence area and proxy water depth based on historical satellite images from 1988 to 2022. Applying inconsistency assessment, it was tried to assess how water appearance at a pixel is inconsistent and how average proxy water depth is inconsistent to attain. Four manmade and natural floodplain wetland complexes were taken for this. The study revealed about 51-53% and 59-86% manmade and natural wetland losses respectively and the IIL was also found significantly higher (30-50%) in the cases of natural wetlands in pre and post-monsoon seasons. The scenario is worse in pre-monsoon season in the natural wetlands. Inconsistency of water depth anomaly (IWDA) was also significantly increased almost in the same trend. Discharge control through hydro-engineering structures like dams, barrages, and embankments; river and wetland connecting tie channel loss; and loss of groundwater support are some crucial reasons behind the hydrological inconsistency of wetlands. Growing loss and IIL are caused for concerned economic and ecological adversity. So, the findings would be very useful for taking necessary planning for wetland management and restoration.

Impact of river flow modification on wetland hydrological and morphological characters.

A good number of researchers investigated the impact of flow modification on hydrological, ecological, and geomorphological conditions in a river. A few works also focused on hydrological modification on wetland with some parameters but as far the knowledge is concerned, linking river flow modification to wetland hydrological and morphological transformation following an integrated modeling approach is often lacking. The current study aimed to explore the degree of hydrological alteration in the river and its effect on downstream riparian wetlands by adopting advanced modeling approaches. After damming, maximally 67 to 95% hydrological alteration was recorded for maximum, minimum, and average discharges. Wavelet transformation analysis figured out a strong power spectrum after 2012 (damming year). Due to attenuation of flow, the active inundation area was reduced by 66.2%. After damming, 524.03 km2 (48.9% of total pre-dam wetland) was completely obliterated. Hydrological strength (HS) modeling also reported areas under high HS declined by 14% after post-dam condition. Wetland hydrological security state (WSS) and HS matrix, a new approach, are used to explore wetland characteristics of inundation connectivity and hydrological security state. WSS was defined based on lateral hydrological connectivity. HS under critical and stress WWS zones deteriorated in the post-dam period. The morphological transformation was also well recognized showing an increase in area under the patch, edge, and a decrease in the area under the large core area. All these findings established a clear linkage between river flow modification and wetland transformation, and they provided a good clue for managing wetlands.