Hydroclimatological Perspective of the Kerala Flood of 2018

Flood is among the deadliest disasters in India, and the frequency of floods and extreme precipitation events is projected to increase under the warming climate. The frequency of floods in India varies geographically as some regions are more prone to floods than the others. The Kerala flood of 2018 caused enormous economic damage, affected millions of people, and resulted in the death of more than 400 people. Here we provide a hydroclimatological perspective on the Kerala flood of 2018. Using the observations and model simulations from the Variable Infiltration Capacity (VIC) model, we show that the 2018 extreme precipitation and runoff conditions that caused flooding were unprecedented in the record of the past 66 years (1951–2017). Our results show that mean monsoon precipitation has significantly declined while air temperature has significantly increased during 1951–2017 in Kerala. The drying and warming trends during the monsoon season resulted in a declined total runoff in large part of the state in the last 66 years. Apart from the mean hydroclimatic conditions, extreme precipitation, and extreme total runoff have also declined from 1951 to 2017. However, 1 and 2-day extreme precipitation and extreme runoff conditions in August 2018 exceeded substantially from the long-term 95^th percentiles recorded during 1951–2017. Since there is no increase in mean and extreme precipitation in Kerala over the last six decades, the extreme event during August 2018 is likely to be driven by anomalous atmospheric conditions due to climate variability rather anthropogenic climate warming. The severity of the Kerala flood of 2018 and the damage caused might be affected by several factors including land use/land cover change, antecedent hydrologic conditions, reservoir storage and operations, encroachment of flood plains, and other natural factors. The impacts of key drivers (anthropogenic and natural) on flood severity need to be established to improve our understanding of floods and associated damage.     

Singular spectrum analysis,harmonic regression and El-Nino effect on total ozone (1979–1993) over India and surrounding regions

The Total Ozone Mapping Spectrometer (TOMS) is a satellite instrument that records Total Column Ozone (TCO) concentration (in DB) of the atmosphere in the form of different overpass files. We have selected 23 sites over India (15), Pakistan (4), Bangladesh (1) and adjoining China (3) to investigate the TCO scenario over this region. About 114,000 historical records (1979M1–1992M12) from 23 overpass files were processed to generate 23 monthly mean time series (TS) of TCO. Statistical analysis followed by singular spectrum analysis (SSA), harmonic regression (HR) and spatial interpolation have been used to accomplish the investigation. Four dominant signals; quasi-biennial signal (QBI, \(\hbox {T} = 30.12\) months), quasi-annual signal (QAN, \(\hbox {T} = 19.69\) months), annual signal (ANN, \(\hbox {T} = 12\) months) and semi-annual signal (SAN, \(\hbox {T} = 6\) months) were discerned to explain the variability. Direct latitudinal effect on the TCO distribution was observed. The variance was limited between 80.53 and 90.13%; ANN contributes 65.93–93.22% followed by SAN 0.58–5.69%, QAN 0.33–5.48%, and QBI 0.06–5.94%. Peak values of the oscillations are estimated from phasor diagrams: QBI, March to May in the mid-latitude; QAN, April, and May; ANN, February to April; SAN, March to May. Incisive pictures of the average distribution and variability of four sinusoids were investigated from contour plots. Two ozone valley were discerned from Spatial interpolation; one over Deccan Plateau in low and other over Tibetan Plateau in high latitude. 179 outliers from \(23 \times 168\) observations have been identified after harmonic regression. The appearance of the outliers is highly consistent with extreme phases of multivariate ENSO Index and Dipole Mode Index.     

Pedotransfer functions to estimate soil water content at field capacity and permanent wilting point in hot Arid Western India

Characterization of soil water retention, e.g., water content at field capacity (FC) and permanent wilting point (PWP) over a landscape plays a key role in efficient utilization of available scarce water resources in dry land agriculture; however, direct measurement thereof for multiple locations in the field is not always feasible. Therefore, pedotransfer functions (PTFs) were developed to estimate soil water retention at FC and PWP for dryland soils of India. A soil database available for Arid Western India (N=370) was used to develop PTFs. The developed PTFs were tested in two independent datasets from arid regions of India (N=36) and an arid region of USA (N=1789). While testing these PTFs using independent data from India, root mean square error (RMSE) was found to be 2.65 and 1.08 for FC and PWP, respectively, whereas for most of the tested ‘established’ PTFs, the RMSE was >3.41 and >1.15, respectively. Performance of the developed PTFs from the independent dataset from USA was comparable with estimates derived from ‘established’ PTFs. For wide applicability of the developed PTFs, a user-friendly soil moisture calculator was developed. The PTFs developed in this study may be quite useful to farmers for scheduling irrigation water as per soil type.     

Geochemistry and distribution of sediments in the East Indian shelf,SW Bay of Bengal: implications on weathering,transport and depositional environment

Forty-two substrate sediment samples and three cores procured from the shelf region between Chennai and Cuddalore were analyzed to understand the spatial and vertical sediment distribution. Samples subjected to grain size, bulk and clay mineralogical analyses, REE and trace element geochemistry yielded interesting results about the sediment characteristics with respect to the modern day environment. The present study revealed that the study area is characterized by high energy environment marked by predominant composition of medium sand. Results confirmed the evidence of more illite than kaolinite, smectite, and chlorite in the clay mineral assemblage indicating a terrigenous source. Geochemical data also revealed that the enrichment of light rare earth elements (LREE) in the sediments is due to continental source of Precambrian times. High feldspar content in the sediments which is emphasized by bulk mineralogical data displayed positive Eu anomaly. By using the paleoredox index, the area of interest is considered to have undergone no major changes in its depositional settings.     

Housing strategies in low income urban communities in Accra,Ghana

As the rent-free compound housing system in Ghana gradually became unpopular, there was the need for state intervention in housing provision. Housing became an important part of the country’s developmental policies through state interventions prior to the late 1970s. The economic crises in 1979 forced the country to opt for Structural Adjustment Programme, compelling the state to relax on its efforts to provide housing for the public. The paper uses the mode of economic integration framework to discuss the various housing forms in the country. It argues, housing provision led by the private sector creates remarked differences between housing for the higher and lower income groups. The study uses two low income communities in Accra to explain different ways by which the urban poor in Ghana accommodate themselves amidst the country’s housing problems. The study concludes there is an alternative to the housing crises in the country which could be found in the public-private investments in the rental form of the compound housing system.     

A GIS based planning support system for assessing financial feasibility of urban redevelopment

Urban densification trends combined with redevelopment increasingly moving away from large former industrial and transport sites toward existing town centres and corridors indicate redevelopment is becoming increasingly complex, difficult to plan for and undertake. The interplay between land and property markets and planning frameworks suggest city planners and urban researchers need new tools and methodologies to gain insights into ways to deliver effective responses. Despite the need, there is a limited availability of comprehensive models to fulfil the task. This paper describes a GIS-based tool to assess parcel-level financial feasibility and housing supply associated with urban redevelopment within a precinct. The tool incorporates existing and potential built form and parameters associated with the planning framework and land and property markets. Using a real case study in a workshop, tool performance was evaluated by professional urban planners in terms of its capacity to produce metrics and visualisations of potential scenarios of redevelopment. Results indicate the usefulness of the tool for emulating land market conditions and testing scenarios of planning regulation and market changes for strategic planning purposes.     

The perception of stakeholders on regional transformation on the outskirts of Yogyakarta City,Indonesia

The research was conducted on the outskirts of Yogyakarta City that administratively include three districts of Sleman Regency, namely Depok, Gamping, and Mlati, and three districts of Bantul Regency, namely Kasihan, Sewon, and Banguntapan. It aimed to obtain a deeper understanding on the perceptions of stakeholders on the regional transformation phenomena occurring on the outskirts of Yogyakarta City. This is a qualitative case study research with a single case. The case study research method was selected because the observed phenomenon is contemporary and the analyzed issue is unique. It used a qualitative method with field observations and in-depth interviews to several informants as data acquisition techniques. The informants were stakeholders from state/government, private sector/entrepreneur, academics, and civil society, which were selected using purposive sampling method. The research data processing and analysis included: (1) data reduction, (2) data presentation, and (3) data conclusion. In order to examine the reliability and validity of the data, the research used source triangulation method. The results showed that all stakeholders perceived the regional transformation on the outskirts of Yogyakarta City to have positive and negative consequences on various dimensions. The positive ones were the economic opportunities, generated by the regional transformation process, for both the native people and the migrants. Aside from these positive consequences, the regional transformation on the outskirts of Yogyakarta City also caused negative impacts on the physical, economic, social, and cultural dimensions of the outskirts.     

Climate variability/change and attitude to adaptation technologies: a pilot study among selected rural farmers’ communities in Nigeria

Understanding climate variability and change is essential for designing adaptation policies and strategies to deal with the impacts of climate change on the agricultural sector. This Paper aims at assessing climate variability/change, the perception of rural farmers on climate change and preferred  adaptation strategies among the farmers in some selected farming communities in Nigeria. The study thus used both meteorology data and social survey, to examine variability/change in climate and factors determining the adaptation techniques adopts by rural farmers. The results show a relatively uniform temperatures and some seasonal variations in recent years (diurnal range of temperature is about 10 °C) but the rainfall shows much more seasonal variations. The rainfall has relatively undeviating trend from 1981 to 1996 but the trend appears to be upwards from the year 1997 to 2010. About 72.8% participants responded in the affirmative that climate is changing but there appears to be a significant relationship between the length of farming experiences and farmers’ perceptions of climate change adaptation techniques. Water-related (about 53%) and nutrient related (about 52%) technologies appear to have a high preference among the farmers. The major driver that determines farmers’ preference for climate change adaptation techniques is their incomes and experiences.     

Spatial and temporal trends of dust storms across desert regions of Iran

Dust storms are among natural and anthropogenic hazards for socioeconomic resources, especially in desert regions. In recent years, dust storms have become a serious problem, especially in desert regions of Iran. This study investigates temporal and spatial variation of dust storm frequency in desert regions of Iran. The number of dusty days (NDD) are collected from 22 stations across the region. The statistical analysis of NDD time series is carried out to show both spatial and seasonal pattern of dust storm occurrence in the region. The regional map of statistical characteristics indicates a north to south increasing dust storm frequency. The spatial map also reveals higher year-to-year variation in south eastern Iran. The seasonality of NDD shows the highest frequency for summer followed by the spring and autumn seasons. The popular Mann–Kendall and the bootstrap MK test to consider serial correlation are then applied for Trend assessment. Results showed both negative (across the north and northwestern regions) and positive trend (across south and south eastern regions) in the annual and seasonal NDD time series. This north-to-south gradient in the spatial and temporal frequency NDD may arise from harsh dry and gusty winds as well as intense land use change in the south eastern territories of Iran. However, more careful and detailed studies are required to connect environmental conditions to change in NDD frequency.