Low-lying Coastal Zones Research Articles

Climate Change and Sea-Level Rise: Impact On Agriculture Along Andhra Pradesh Coast—A Geomatics Analysis

Climate change due to anthropogenic forcing through escalating greenhouse gas emissions and destruction of carbon sinks by deforestation is leading to floods and droughts affecting agriculture production. Global warming induces steric as well as eustatic rise in sea-level, by thermal expansion and addition of ice-melt water, respectively. Although the IPCC (2007) estimated a maximum possible sea-level rise of about 59 cm, more recent estimates show a global average rise of ≥1 m by the 2100 AD. The low-lying coastal zones are more vulnerable to rising sea levels as they face submergence or saltwater intrusion which affects the agriculture activities. Geomatics-based models on the possible impact of the predicted sea-level rise on coastal agriculture are necessary to initiate appropriate mitigation plans. The present study is an attempt in this direction taking the Andhra Pradesh (AP) coast as an example. The land use / land cover of the AP coast was mapped through the interpretation of IRS-P6 LISS III imagery from 2008. SRTM digital elevation models coupled with landform evidences have been used to interpolate contours at 0.5 m interval, although highly approximate, for the entire coastal region. If the sea level rises by 1.0 m, about 4040 km2 area including the present intertidal wetlands as well as the land between the present and future high tide lines would be affected along the entire 1030-km-long AP coast displacing about 1.67 million inhabitants and their economic activities, in about 351 revenue villages. The low-lying Krishna-Godavari delta region in the central part of the AP coast would be the worst affected zone as 2205 km2 of its area including about 1593 km2 under various types of agricultural activities is lying within the future high tide limit of 2.5 m elevation.

Climate Change and Asia’s Coastal Urban Cities

The scientific literature has documented the growing risks of flooding posed for Asia’s coastal cities by the combination of climate change, as reflected in sea level rise and intensified storms and storm surges, and ongoing urban growth in low-lying coastal zones. These issues were already elaborated in the 2007 IPCC (IPCC, 2007) reports but recent studies indicate that climate change, sea level rise and the sinking of the deltas on which most Asian mega urban regions have arisen, are all occurring at much faster rates than earlier projected and therefore pose even greater risks than previously indicated. Global warming appears to be accelerating and may increase to 4° C or more by the end of this century, twice the earlier IPCC projections. The sea level is now expected to rise by one meter or more by 2100; two or three times the earlier projections. The recent typhoons and rains striking Southeast Asia have been the most intense in decades as would be expected as a result of global warming. At the same time, Asia’s urban population is increasing at the rate of 140,000 per day, with much of this growth occurring in low-lying coastal regions and on deltas characterized by land subsidence that is further contributing to flooding risks. While these risks and vulnerabilities have been increasingly detailed in the scientific literature, recognition and effective responses on the part of the urban planning and policy community have been slow to develop. Barriers to adaptation, policy formation and response are reviewed and possible steps forward are outlined.

Sea level trend reversal: Land uplift outpaced by sea level rise on Scotland's coast

A widely held belief persists that rising land levels since the latter part of the last glaciation will help safeguard much of the Scottish coast from the impact of global sea level rise. Although the landforms of much of Scotland's coast reflect long-term land uplift, recent investigations show that uplift rates are now modest and are less than rising sea levels. When comparisons are made between long-term land-level changes using Glacio-Isostatic Adjustment models, representative of the last few thousand years (Shennan and Horton, 2002; Shennan et al., 2009), and recent land-level changes using Continuous GPS records, representative of the last decade (Bradley et al., 2006), it is apparent that recent rates of uplift are slower than longer-term averages. We show here that when tidal records are considered, they show marked increases over recent decades although the extent to which these are part of a longer-term trend is uncertain. When considered alongside the UKCP09 climate projections, these tidal observations are of value in narrowing or calibrating the wide choice of sea level projections under various climate change scenarios. It appears that Scotland's observed tidal record now lies close to the 95% projection of the UKCP09 High Emission Scenario and isostatic uplift now contributes little towards mitigating the effect of relative sea level rise on the Scottish coast. If the observed recent patterns are maintained, this has significant implications for strategic planning, flood risk management and sustainable development on Scotland's coast, and particularly on low-lying coastal zones around the major cities.

Implications of Sea-Level Rise for Estonia

Abstract Estonia is a coastal country with a long coastline (3800 km) for which climate change and accelerated sea-level rise are key problems that need to be considered in any future impact assessment. Due to its flat, low-lying coastal zone, any rise in sea level places many coastal ecosystems and recreationally valuable sandy beaches at risk. Milder winters, combined with increased storminess and the absence of sea-ice cover, would exacerbate these impacts. However, isostatic uplift and the distance of coastal settlements from the present coastline could reduce these risks. This paper presents the potential impact of a 1-m global sea-level rise by 2100 if no adaptation is undertaken. Seven representative study areas, characterising all shore types in Estonia, were selected for sea-level rise vulnerability and adaptation assessment. The diverse structure of Estonia's coasts, the rapidly migrating shorelines, and the abundance of small islands were found to complicate reliable predictions regarding clima...

Late glacial impacts on dispersal and colonization of Atlantic Canada and Maine by freshwater fishes

Late glacial scenarios of ice retreat and biogeography databases constrain the dispersal routes of obligate freshwater fishes into Atlantic Canada and Maine. Evidence indicates glacial ice covered the present-day mainland and offshore islands at 18,000 14C yr before present. Possible refugia for extirpated freshwater fishes were the exposed outer edge of the Grand Banks (east), exposed Georges Bank (south-Atlantic Refugium), and the Mississippi Refugium in the west. It is improbable that the region was recolonized from the offshore refugia. Rather, fishes recolonized from the east via the upper St. Lawrence River valley into the upper Saint John River, Maine (Lake Madawaska) from 11,000 to 12,000 14C yr BP. The short period of entry resulted in the low diversity of obligate freshwater species in the region. Lake Madawaska was breached and dispersal continued into the remainder of the region after 8000 14C yr BP. By 6000 14C yr BP, access routes to the east along low-lying coastal zones were blocked by rising sea levels, which isolated Prince Edward Island, Cape Breton Island, and most probably Nova Scotia. Natural dispersal across the region appeared complete by this time.

Vulnerability of Hampton Roads, Virginia to Storm-Surge Flooding and Sea-Level Rise

Sea-level rise will increase the area covered by hurricane storm surges in coastal zones. This research assesses how patterns of vulnerability to storm-surge flooding could change in Hampton Roads, Virginia as a result of sea-level rise. Physical exposure to storm-surge flooding is mapped for all categories of hurricane, both for present sea level and for future sea-level rise. The locations of vulnerable sub-populations are determined through an analysis and mapping of socioeconomic characteristics commonly associated with vulnerability to environmental hazards and are compared to the flood-risk exposure zones. Scenarios are also developed that address uncertainties regarding future population growth and distribution. The results show that hurricane storm surge presents a significant hazard to Hampton Roads today, especially to the most vulnerable inhabitants of the region. In addition, future sea-level rise, population growth, and poorly planned development will increase the risk of storm-surge flooding, especially for vulnerable people, thus suggesting that planning should steer development away from low-lying coastal and near-coastal zones.