Comparison of sea-ice freeboard distributions from aircraft data and cryosat-2

The only remote sensing technique capable of obtain- ing sea-ice thickness on basin-scale are satellite altime- ter missions, such as the 2010 launched CryoSat-2. It is equipped with a Ku-Band radar altimeter, which mea- sures the height of the ice surface above the sea level. This method requires highly accurate range measure- ments. During the CryoSat Validation Experiment (Cry- oVEx) 2011 in the Lincoln Sea, Cryosat-2 underpasses were accomplished with two aircraft, which carried an airborne laser-scanner, a radar altimeter and an electro- magnetic induction device for direct sea-ice thickness re- trieval. Both aircraft flew in close formation at the same time of a CryoSat-2 overpass. This is a study about the comparison of the sea-ice freeboard and thickness dis- tribution of airborne validation and CryoSat-2 measure- ments within the multi-year sea-ice region of the Lincoln Sea in spring, with respect to the penetration of the Ku- Band signal into the snow

Does Rainwater Harvesting Contribute to Fight Climate Change and Women Empowerment in Bangladesh?

Agriculture, domestic, and industry rely on water resources systems for fulfilling water demand while water resources systems face both climate-induced extreme events and management and governance problems. These constraints lead to a mismatch between demand and supply of water for those sectors. This study applies central tendency and variability to analyze data and mixed methods approach to interpret the result. Throughout 1999-2019, the growth rate of population, gross domestic product, and urban population is 1.354%, 6.084%, and 3.70% correspondingly, contributing to increased water demand. However, average groundwater depletion increased from 2.455km3 (1989-1990) to 4.9016km3 while average flood-affected areas enhanced by 8,644km2 in 2014-2018 compared to 1988-1993. Furthermore, salt-affected areas incremented by 2,22,810ha in 2009 contrasted to 1973, whereas the mean wind speed of cyclones increased by 30.02km in 2015-2020 compared to 1988-1995. The mean sea-level rise increased by 16.8cm and 169.2cm in 1995-2000 compared to 1979-1983 in Cox’s Bazar and Char Changa station, respectively. The current approach to address the mismatch may not be effective as a long-term solution due to climate change and geographical context so that this study urges policy makers to shift their focus on water sources for addressing the gap between water demand and supply in Bangladesh. This study will create attention of policymakers, water managers, water experts, and academics for further study in adaptation with climate extreme events which impact on water resources, damage social economic and enviornmnetal assets, and displaced people. It also urges finding and accommodating a sustainable approach to reducing the water demand-supply gap. This study is relevant for various government organizations dealing with water resources management, policymakers, and professionals in water resources management and governance. Sustainable water resources management is one of the significant factors in achieving sustainable development goals and alleviating poverty. Since sustainable development is a multidimensional concept, it is influenced by different factors like water access, poverty, socioeconomic development. Rainwater collection and use are ways to ensure sustainable water resources management and increase water access where formal water suppliers fail to address the water crisis. This research explores what key factors influence the economic benefit of rainwater harvesting using Ordinary Least Square regression on primary data collected from 1040 households at a subdistrict of southwestern Bangladesh. Six factors have been measured the price of water, age of rainwater harvesting, the total cost of rainwater harvesting, storage capacity, number of children, and income. It is the first kind of empirical research that connects rainwater harvesting, economic advantage, and econometric analysis. The empirical result shows that income (1.253***), storage capacity (49.425***), price of water (80669.9***), age of rainwater harvesting (8740.16***), and total cost (1.649***) have positive correlation with economic benefit while the number of children (-3501.90***) has a negative. It concluded that economic benefit from rainwater harvesting could be improved by including in water management policy or different policies for rainwater harvesting, particularly for the rain-intensive country. Moreover, it can be a tool to alleviate poverty and achieve sustainable development goals through increasing water access. However, context specificity and multidimensionality is the limitation of this study. Water security has been long connected with facilitating women empowerment that is more crucial in developing countries. The rising water demand may hamper water security, leading to a constraint empowerment process. Women empowerment is rising in Bangladesh, but the connection between water security through rainwater harvesting and women empowerment is the first study in this circumstance. It may provide an alley to determine the connection between water security ensured by rainwater harvesting and empowerment. This quantitative study explored the survey data of 1051 households to measure the possibility of economic, social, and political empowerment through water security. The result shows that economic, social, and political empowerment has a positive and statistically significant relation with water security, but context specificity indicates that interpretation of the findings is not uncomplicated. Moreover, male household head, income, number of family members, and operating rainwater harvesting negatively influence water security level while the cost to build up rainwater harvesting infrastructure, storage capacity, and land ownership positively influences water security. Based on the results, policies and programs that stimulate women's empowerment need more understanding and strategies concerning water security and empowerment for gender equality and achieve sustainable development goals five and six

Developing a Strategic Process to Reintroduce a Lost Water Way as a Possible Solution for Water Logging: Case study, An Area of Dhaka Metropolitan City

During the rainy season, Dhaka, the capital city of Bangladesh, faces tremendous rainfall which is annually 1600mm-2000 mm and it is increasing at a rate of 55.90 mm/year. So, in monsoon, some areas of this city suffer from water logging which continues from 3 hours up to two feet to more than one day. It increases the hazards for everyday life for the city dwellers, especially in the transportation and working sectors of the city which follows other socio-economic, health and environmental problem. Dhaka is one of the most populous cities in the world. This area is almost flat and close to sea level. So, Dhaka is susceptible to flood during monsoon. Historically Dhaka has a network of natural canals which was connected to big rivers to serve as a natural drainage system for the rain runoff. These canals served as a good means of transportation also. Gradually, in the course of time this natural drainage system has been almost destroyed. Due to overpopulation, the increasing demand for land and unplanned rapid urbanization causes the destruction and discontinuation of water channels. As a result, waterlogging occurs during the rainy season in various part of the city. Demolition of these water channels and depressions not only affects the natural process of land formation but also alter the ecosystem. This study aims to develop a process to reintroduce a previous waterway in Dhaka city as a possible solution of waterlogging. So, at first, changes in wetlands and water bodies are analyzed through studying the geo-morphological history of Dhaka and ArcGIS analysis to find out the potential water bodies which are needed to be revived or developed further. Hydrological analysis in ArcMap has been done here to show the water flow direction which is derived from the DEM (digital elevation model) of Dhaka city. Then, one disconnecting point is chosen to develop a process for introducing waterway as a possible solution of waterlogging which will also serve as a transportation system. The study only provides a generic idea to verify an idea to resolve the issue of urban waterlogging. The most positive aspect of this proposal is to protect the urban water bodies and convert those as a mean of the transportation system. Without protecting the wetlands and water bodies the drainage system of Dhaka will collapse and inundation will increase. If the method works then, it will be a key factor to make other dead water lines alive for Dhaka City

Application of open-access and 3rd party geospatial technology for integrated flood risk management in data sparse regions of developing countries

Floods are one of the most devastating disasters known to man, caused by both natural and anthropogenic factors. The trend of flood events is continuously rising, increasing the exposure of the vulnerable populace in both developed and especially developing regions. Floods occur unexpectedly in some circumstances with little or no warning, and in other cases, aggravate rapidly, thereby leaving little time to plan, respond and recover. As such, hydrological data is needed before, during and after the flooding to ensure effective and integrated flood management. Though hydrological data collection in developed countries has been somewhat well established over long periods, the situation is different in the developing world. Developing regions are plagued with challenges that include inadequate ground monitoring networks attributed to deteriorating infrastructure, organizational deficiencies, lack of technical capacity, location inaccessibility and the huge financial implication of data collection at local and transboundary scales. These limitations, therefore, result in flawed flood management decisions and aggravate exposure of the most vulnerable people. Nigeria, the case study for this thesis, experienced unprecedented flooding in 2012 that led to the displacement of 3,871,53 persons, destruction of infrastructure, disruption of socio-economic activities valued at 16.9 billion US Dollars (1.4% GDP) and sadly the loss of 363 lives. This flood event revealed the weakness in the nation’s flood management system, which has been linked to poor data availability. This flood event motivated this study, which aims to assess these data gaps and explore alternative data sources and approaches, with the hope of improving flood management and decision making upon recurrence. This study adopts an integrated approach that applies open-access geospatial technology to curb data and financial limitations that hinder effective flood management in developing regions, to enhance disaster preparedness, response and recovery where resources are limited. To estimate flood magnitudes and return periods needed for planning purposes, the gaps in hydrological data that contribute to poor estimates and consequently ineffective flood management decisions for the Niger-South River Basin of Nigeria were filled using Radar Altimetry (RA) and Multiple Imputation (MI) approaches. This reduced uncertainty associated with missing data, especially at locations where virtual altimetry stations exist. This study revealed that the size and consistency of the gap within hydrological time series significantly influences the imputation approach to be adopted. Flood estimates derived from data filled using both RA and MI approaches were similar for consecutive gaps (1-3 years) in the time series, while wide (inconsecutive) gaps (> 3 years) caused by gauging station discontinuity and damage benefited the most from the RA infilling approach. The 2012 flood event was also quantified as a 1-in-100year flood, suggesting that if flood management measures had been implemented based on this information, the impact of that event would have been considerably mitigated. Other than gaps within hydrological time series, in other cases hydrological data could be totally unavailable or limited in duration to enable satisfactory estimation of flood magnitudes and return periods, due to finance and logistical limitations in several developing and remote regions. In such cases, Regional Flood Frequency Analysis (RFFA) is recommended, to collate and leverage data from gauging stations in proximity to the area of interest. In this study, RFFA was implemented using the open-access International Centre for Integrated Water Resources Management–Regional Analysis of Frequency Tool (ICI-RAFT), which enables the inclusion of climate variability effect into flood frequency estimation at locations where the assumption of hydrological stationarity is not viable. The Madden-Julian Oscillation was identified as the dominant flood influencing climate mechanism, with its effect increasing with return period. Similar to other studies, climate variability inclusive regional flood estimates were less than those derived from direct techniques at various locations, and higher in others. Also, the maximum historical flood experienced in the region was less than the 1-in-100-year flood event recommended for flood management. The 2012 flood in the Niger-South river basin of Nigeria was recreated in the CAESAR-LISFLOOD hydrodynamic model, combining open-access and third-party Digital Elevation Model (DEM), altimetry, bathymetry, aerial photo and hydrological data. The model was calibrated/validated in three sub-domains against in situ water level, overflight photos, Synthetic Aperture Radar (SAR) (TerraSAR-X, Radarsat2, CosmoSkyMed) and optical (MODIS) satellite images where available, to access model performance for a range of geomorphological and data variability. Improved data availability within constricted river channel areas resulted in better inundation extent and water level reconstruction, with the F-statistic reducing from 0.808 to 0.187 downstream into the vegetation dominating delta where data unavailability is pronounced. Overflight photos helped improve the model to reality capture ratio in the vegetation dominated delta and highlighted the deficiencies in SAR data for delineating flooding in the delta. Furthermore, the 2012 flood was within the confine of a 1-in-100-year flood for the sub-domain with maximum data availability, suggesting that in retrospect the 2012 flood event could have been managed effectively if flood management plans were implemented based on a 1-in-100-year flood. During flooding, fast-paced response is required. However, logistical challenges can hinder access to remote areas to collect the necessary data needed to inform real-time decisions. Thus, this adopts an integrated approach that combines crowd-sourcing and MODIS flood maps for near-real-time monitoring during the peak flood season of 2015. The results highlighted the merits and demerits of both approaches, and demonstrate the need for an integrated approach that leverages the strength of both methods to enhance flood capture at macro and micro scales. Crowd-sourcing also provided an option for demographic and risk perception data collection, which was evaluated against a government risk perception map and revealed the weaknesses in the government flood models caused by sparse/coarse data application and model uncertainty. The C4.5 decision tree algorithm was applied to integrate multiple open-access geospatial data to improve SAR image flood detection efficiency and the outputs were further applied in flood model validation. This approach resulted in F-Statistic improvement from 0.187 to 0.365 and reduced the CAESAR-LISFLOOD model overall bias from 3.432 to 0.699. Coarse data resolution, vegetation density, obsolete/non-existent river bathymetry, wetlands, ponds, uncontrolled dredging and illegal sand mining, were identified as the factors that contribute to flood model and map uncertainties in the delta region, hence the low accuracy depicted, despite the improvements that were achieved. Managing floods requires the coordination of efforts before, during and after flooding to ensure optimal mitigation in the event of an occurrence. In this study, and integrated flood modelling and mapping approach is undertaken, combining multiple open-access data using freely available tools to curb the effects of data and resources deficiency on hydrological, hydrodynamic and inundation mapping processes and outcomes in developing countries. This approach if adopted and implemented on a large-scale would improve flood preparedness, response and recovery in data sparse regions and ensure floods are managed sustainably with limited resources

Earth resources: A continuing bibliography with indexes (issue 58)

This bibliography lists 500 reports, articles, and other documents introduced into the NASA scientific and technical information system between April 1 and June 30, 1988. Emphasis is placed on the use of remote sensing and geophysical instrumentation in spacecraft and aircraft to survey and inventory natural resources and urban areas. Subject matter is grouped according to agriculture and forestry, environmental changes and cultural resources, geodesy and cartography, geology and mineral resources, hydrology and water management, data processing and distribution systems, instrumentation and sensors, and economic analysis