Agriculture is the mainstay of economy in Malawi -the warm heart of Africa. It employs 85 % of the labour force, and produces one third of the Gross Domestic Product (GDP) and 90 % of foreign exchange earnings. Maize farming covers over 92 % of Malawi's agricultural land and contributes over 54 % of national caloric intake. With a subtropical climate and~99 % rainfed agriculture, Malawi relies heavily on precipitation for its agricultural production. Given the significance of rainfed maize for the nation's labour force and GDP, we have investigated climate change effects on this staple crop. We show that rainfed maize production in the Lilongwe District, the largest maize growing district in Malawi, may decrease up to 14 % by mid-century due to climate change, rising to as much as 33 % loss by the century's end. These declines can substantially harm Malawi's food production and socioeconomic status. Supplemental irrigation, crop diversification and natural conservation methods are promising adaptation strategies to improve Malawi's food security and socioeconomic stability.
Abstract:Measurement/estimation of snow water equivalent (SWE) is a difficult task in water resources studies of snowy regions. SWE point data is measured at snow courses that are normally operated with low density owing to high costs and great difficulty in reaching the stations in cold seasons. Moreover, snow is known to exhibit high spatial variability, which makes SWE studies based solely on sparse station data more uncertain. Ever-increasing availability of satellite images is a promising tool to overcome some of the difficulties associated with analyzing spatial variability of snow. Although National Oceanic and Atmospheric Administration (NOAA) satellite images have low spatial resolution with approximately 1.1-km pixel size, they are adequate for mapping snow cover at regional scales and enjoy a moderate length of record period. In this paper, rain and snow records of synoptic stations and the time series of NOAA-based snow cover maps were used to map average SWE of a vast area in southwestern Iran. First, monthly and annual snow coefficient (SC) at synoptic stations were determined on the basis of analysis of hourly observation of type and amount of precipitation. Then, two new spatially distributed snow characteristics were introduced, namely, average frequency of snow observation (FSO) and monthly frequency of maximum snow observation (FMSO), on the basis of existing satellite snow observations. FSO and monthly FMSO maps were prepared by a geographic information system on the basis of snow map time series. Correlation of these two parameters with SC was studied and spatial distribution of SC was estimated on the basis of the best correlation. Moreover, the distribution of mean annual precipitation was derived by comparing a number of interpolation methods. SWE map was generated by multiplying SC and precipitation maps and its spatial variability in the region was analyzed.
The coastal areas of Florida, United States, are exposed to increasing risk of flooding due to sea level rise as well as severe hurricanes. Florida regulations suggest constructing stormwater retention ponds as an option to retain excess runoff generated by the increased impervious area and to protect the environment by reducing pollutants from new developments. Groundwater level rise can significantly lower the soil storage capacity and infiltration at retention ponds, in turn, reducing the pond's capacity to capture consecutive storms due to longer pond volume recovery time. Partial groundwater inundation can affect retention ponds' ability to decrease peak flow rates and keep the post-development outflow lower than or equal to pre-development conditions. In this paper, the reliability and performance of a retention pond near Tampa Bay, Florida, was evaluated under sea level rise conditions. An integrated surface water and groundwater model was developed, and the groundwater table was projected for future conditions as a function of sea level rise. The results showed that sea level rise could increase the seasonal high water elevation of the retention pond up to 40 cm by mid-21st century. This increase lowered the reliability of the retention pond by about 45%. The pond failed to recover the designed treatment volume within required 72 h because of the high groundwater table, increasing the risk of pollutant discharge. Furthermore, the peak flow and volume of runoff significantly increased under sea level rise and associated groundwater table rise conditions. The study results suggest that it is imperative to consider future sea level rise conditions in stormwater design in low-lying coastal areas of Florida and around the world to prevent poor pond performance and increased risk of flooding in the future.Most of the studies on climate change and flooding issues have addressed anthropogenic changes of rainfall intensity and frequency as well as land-use changes due to development and urbanization [8][9][10]. These changes substantially alter the peak flow, volume, and duration of flooding and exacerbate domestic inundation areas [11]. In addition to impacts due to rainfall and land-use changes, there is a significant marine flooding risk to highly-populated low-lying cities in coastal areas, including major economic centers such as London, New York, Shanghai, and Mumbai [12]. Globally, it is estimated that more than 20 million people live below the normal high tide elevation and more than 200 million people are under threat of extreme sea level events caused by storms [12]. The United States National Oceanic and Atmospheric Administration (NOAA) reports that about 3.2 billion people worldwide live and work within 200 km of a coastline [13,14], which can be adversely affected by SLR-related closure of access roads and reduced functionality of other infrastructure.In the United States, the state of Florida ranked 3rd for the number of National Flood Insurance Program (NFIP) claims in the last four decades [15]. T...
The south coastal area of Iran, being adjacent to the humidity of the Persian Gulf and Oman Sea in addition to its high temperature and its high capacity for absorbing humidity, has a great potential for water harvesting from fog and air humidity. In this research, data have been collected from 10 synoptic stations adjacent to the Persian Gulf and Oman Sea, in order to investigate water harvesting from fog and air humidity. The data used in this study included hourly dry and wet temperature, relative humidity, wind direction and velocity and dew point temperature. By the use of these data, various parameters such as atmospheric water vapour pressure, saturated vapour pressure and the absolute humidity of the atmosphere were estimated. Finally, according to the investigations carried out in this study, it was clear that the cited regions had the potential to harvest fog water for 160-360 days. This is whilst the average number of foggy days in the region is 41 maximally. In addition the annual mean water harvested through this technique varies between 6.7 l m À2 day À1 at Abadan station and 156 l m À2 day À1 at Chabahar station. It is worth noting that the maximum amount of water harvested from the stations near the coastal areas occurs during the summer while at stations far from the coastal areas this happens during the winter. Copyright © 2013 John Wiley & Sons, Ltd. RÉSUMÉLa zone côtière du sud de l'Iran étant adjacente au golfe Persique et à la mer d'Oman, elle a un potentiel élevé de récupération de l'eau contenue dans le brouillard et l'humidité de l'air à cause de sa température élevée et sa grande capacité d'absorption d'humidité. Dans cette recherche, les données ont été recueillies auprès de 10 stations météorologiques de la région côtière du golfe Persique et de la mer d'Oman pour mesurer le potentiel de la récolte de l'eau contenue dans le brouillard et l'humidité de l'air. Les données utilisées dans cette étude sont les températures sèche et humide, l'humidité relative, la direction et la vitesse du vent et la température du point de rosée, toutes recueillies au pas de temps horaire. Ces données ont permis d'estimer différents paramètres tels que la pression de vapeur d'eau de l'atmosphère, la pression de vapeur saturante et l'humidité absolue de l'atmosphère. Il résulte que les régions citées ont la potentialité de récolter l'eau du brouillard pendant 160 à 360 jours, alors que le nombre moyen de jours brouillard dans la région est de 41 au maximum. En outre, le volume d'eau annuel moyen récolté par cette technique varie entre 6,7 l m À2 jour À1 à la station Abadan à 156 l m À2 jour À1 à la station de Chabahar. A noter que le maximum d'eau récoltée des stations à proximité des zones côtières se passe pendant l'été alors que celui des stations situées loin des zones côtières se passe pendant l'hiver.
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