ghana climate change vulnerability and adaptation assessment

DESERTIFICATION“Desertification” as defined by the United Nations Convention to Combat Desertification means landdegradation in arid, semi-arid, and dry sub-humid areas resulting from various factors, including climaticvariations and human activities (UNCCD, 1994; 2002). Land degradation, which in drylands can lead todesertification, is one of the consequences of mismanagement of land and results frequently from a mismatchbetween land quality and land use (Beinroth et al., 1994). Activities that can degrade drylands include highpopulation densities, uncontrolled urbanization, land over-exploitation (e.g., excessive use of marginal lands, shortbush fallow periods), misplanning of large agricultural projects, mechanized farming, overgrazing, bad irrigationpractices, mismanagement of land input and neglect of land improvement, inappropriate land use systems andpolicies, bush and forest fires, deforestation, and mining and prospecting. Along with these human-causedfactors, a range of natural factors appear to influence the process of land degradation (e.g., soil types, year-roundaridity, high variability or energy in rainfall, recurrent drought) (Virmani et al., 1994; Reich et al., 2001; UNCCD,2002; EPA, 2003).When land degradation causes desertification, soil productivity diminishes, food production decreases, andvegetative cover is lost. Desertification can even negatively impact areas not directly affected by its symptoms, forexample by causing floods, increasing soil salinization, decreasing water quality and quantity, and increasingsedimentation of natural waters and reservoirs (EPA, 2003; Andah and Gichuki, 2005).VULNERABILITY AND RISK OF DESERTIFICATION IN GHANAThree ecological zones in Ghana are classified as drylands based on the aridity index (ratio of mean annualprecipitation to mean annual potential evapotranspiration, UNEP, 1997). These are the Sudan, Guinea, andCoastal savanna zones with aridity indices of 0.60, 0.60, and 0.54, respectively (EPA, 2003), which place the zonesin the dry sub-humid category of drylands (UNEP, 1997). The administrative regions within these zones are theUpper East, Upper West, Northern, Greater Accra, Central, and Volta (EPA, 2003). Rainfall is unimodal in theGuinea and Sudan savanna zones and is concentrated into about four to six months of the year, with theremaining period being dry. During the long dry season, bush and forest fires are frequent because of the drynessof the atmosphere (i.e., low humidity, high evapotranspiration) and availability of combustible materials. The fires,overgrazing, and other poor land use practices (Table 6.3) leave much of the landscape essentially barren. Theperiod of excessive, highly erosive rainfall occurring just after the prolonged dry period predisposes these areas,which have erodible and low infiltration soils, to a high risk of land degradation, particularly from erosion. In theCoastal Savanna and the Forest-Savanna Transition zones, rainfall is bimodal, but the minor wet season isunreliable. In these areas considerable variation exists between successive rainy seasons in time of onset, duration,spatial distribution, amount of rainfall, and number of rainy days. These conditions contribute to reductions invegetative cover, crop yield, and food security in the affected areas (EPA, 2003).GHANA CLIMATE CHANGE VULNERABILITY AND ADAPTATION ASSESSMENT 93