SOLOMON ISLANDS Point Cruz Yacht Club, Honiara
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SOLOMON ISLANDS Point Cruz Yacht Club, Honiara 1. COUNTRY INTRODUCTION It ranges from sizeable rivers on the larger mountainous islands with dense rainforests, to Description: those small low-lying atolls and islets which rely The Solomon Islands are comprised of about upon rainwater harvesting and maybe a thin fresh 1000 very scattered islands of diverse size. These water lens for their freshwater needs. For example islands have a total land area of 28,370 square Honiara has abundant water in the Lungga kilometres consisting of volcanic peaks rising up River but limited means and financial resources to 2,500 metres, and low lying coral islands less to extract, treat, and reticulate it. Much of the than 3m above sea level. The Solomon Islands are water provided for Honiara is sourced from small divided into 9 provinces with a total population streams, springs and groundwater abstraction of approximately 523,000 (2009 estimate) who are bores. almost exclusively of Melanesian decent. Island Vulnerability: Economy: Cyclones, flooding, drought and seismic events The economy consists of a mixed subsistence periodically affect the Solomon Islands. Sea level agriculture, fishing, and forestry on which over rise also poses a threat to the smaller low islands. 80% of the population depend. Log exports Soil erosion and increased sediment load in rivers and fisheries remain the major foreign exchange result from human activities such as large scale earner for the country. Over-reliance on single clearing from mining and logging activities, as commodities magnify the country’s susceptibility well as impacts from traditional subsistence slash to external shocks. The islands are rich in mineral and burn farming, increasing urban development resources but these are comparatively under and residential housing. Potential pollution and developed apart from the Gold Ridge mine which contamination of water resources have been was scheduled for reopening in early 2011. identified from untreated domestic sewage, small industry discharges (eg fish processing), Water Availability: hydrocarbons from oil storage tanks, mine Water resources availability in Solomon Islands drainage and leaching discharges from mine varies considerably for each island but on the waste, and residues of agricultural fertilizers and larger islands can be considered as very abundant. pesticides. The extent of this contamination is CATALOGUE OF RIVERS FOR PACIFIC ISLANDS Page 122 Site refurbishment, Lungga River, Guadalcanal currently not well understood due to a lack of sector and has little impact on watershed and recent data. coastal ecosystems at present. Tourism numbers reached 13,748 in 2007 (Solomon Islands Power generation: National Statistics Office). The Solomon’s has significant potential for hydropower generation for large, mini and micro hydroelectricity. Apart from some small localised 2. GEOGRAPHIC community mini and micro plants, there has The scattered archipelago of the Solomon Islands, been no substantial investment in this sector about 1,000 mountainous islands and low- that has progressed beyond a feasibility study to lying coral atolls, lie east of Papua New Guinea energy production. and northeast of Australia in the South West 0 0 Health: Pacific Ocean, between latitudes 5 and 12 S of the equator and longitude 1550 and 1700E. Water quality analysis available within the The islands include the large high islands of Solomon Islands is limited. Faecal coliform and Guadalcanal, Malaita, Santa Isabel, San Cristóbal, high nutrients have been detected in samples Choiseul, New Georgia, and the Santa Cruz taken from boreholes with the indication Group with many diverse smaller islands. The that waste water leachate contamination from island chains together measure some 1500 kms overflowing septic tanks during heavy rains is a in total length. The islands in the archipelago common occurrence and is impacting on water are of two types: they are either of volcanic supplies. origin or are coral atolls. The six main islands in Environment and Tourism: the group are volcanic, and are mountainous, blanketed with dense rain forests, with some of Solomon Islands is recognised for its high level the volcanoes on the islands considered active. of biological diversity in terrestrial and marine The lowest point on the islands is the coral environments. The coral reefs, shallow lagoons atolls at only a few metres above sea level, while and mangroves of Solomon Islands are amongst the highest is Mount Popomanaseu at 2,310m, the most biologically diverse in the world. on the Island of Guadalcanal. The island chain However, many reefs appear to be currently experiences regular seismic activity, more recently at most risk due to continued exploitation in 2007, a devastating earthquake and tsunami for food and other resources through the use was experienced in the western province with of unsustainable and destructive harvesting dozens of lives being lost and thousands being methods. Industrial, agricultural and sewage dislocated. The provincial capital of Gizo was pollution of water courses, logging and coastal the worst hit area. The capital city of Honiara is development also threaten coastal, reef and located on the north of Guadalcanal Island. mangrove habitat. Tourism is still a very small Page 123 SOLOMON ISLANDS Map of Solomon Islands Source: CIA World Factbook, 2007 Map of Guadalcanal Island showing Lungga River catchment (after Falkland and Abawi, 2006) CATALOGUE OF RIVERS FOR PACIFIC ISLANDS Page 124 Solomon Islands Geological Map 1983 http://eusoils.jrc.ec.europa.eu/esdb_archive/EUDASM/Asia/lists/coc.htm 3. CLIMATIC the Northwest monsoon season, with reduced rainfall during February when the equatorial The Solomon Islands has a climate typical of trough is normally furthest south. Locations many tropical areas, being characterised by on the southern sides of the larger islands also moderately high and uniform temperature and tend to have a rainfall maximum between June humidity, with abundant rainfall in all months, and September. As there are no rainfalls stations in most areas, especially in the mountains. at altitude (with long-term averages) the effect The range of average maximum temperature of increasing rainfall with height above mean deviation is approximately 20C throughout sea level is unrecorded and an isohyetal map is the year. Rainfall is the least uniform of the currently not available. Depending on the local climatic elements, as topographical effects cause topography, rainfall will increase with elevation, significant variations between locations. The with a maximum falling expected at about the average annual rainfall is mostly within the range 600 to 1,000 metres level on windward slopes. It of 3,000 to 5,000 millimetres with the majority is possible that the heaviest average yearly rainfall of monthly rainfall amounts in excess of 200 could reach up to 9,000mm at some elevated millimetres, with the exception of Honiara which sites. The extreme falls seem to be confined to the experiences a distinct dry period from May transition months of December and April when to November. The wettest months are during Page 125 SOLOMON ISLANDS Lungga Gorge, site of possible hydroelectric power plant the equatorial trough is migrating across the islands. The islands because of their proximity to the equator, are less subject to the damaging effects of tropical cyclones than elsewhere in the southwest Pacific, though cyclones still pose a serious threat each year. Additionally due to the low latitudes of the Solomon’s, atmospheric pressure has only a small variation from month to month, recording little change from day to day except when a tropical cyclone is in the area. Monthly Mean Climate Data for Honiara, Guadacanal Period for Observation Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Annual Item the Mean Temperature Jan 2000 – 27.5 27.2 27.4 27.2 27 26.5 26.5 26.2 26.8 26.9 27.4 27.4 27.0 (ºC) Dec 2008 Precipitation Nov 1954 262 288 297 187 132 89 96 95 96 130 149 208 1937 (mm) – Aug 2009 Source: Solomon Islands Meteorological Service Monthly Mean Rainfalls Honiara, Guadalcanal CATALOGUE OF RIVERS FOR PACIFIC ISLANDS Page 126 Rove Stream, Honiara botanical gardens, stream gauging Prior to the implementation of Pacific HYCOS, 2007-2010, the NHS had in large ceased to operate a regular field program with no operational automatic raingauges. To address this shortfall, 6 automatic raingauges were installed in the Honiara and Guadalcanal Plains area, including one at the main Solomon Islands Meteorological Service synoptic station located at Henderson Field, Honiara International Airport. Apart from the long term Solomon Islands Meteorological Service, SIMS, daily data, there is no available data for short or long term rainfall analysis. The following table identifies the new rainfall stations. Rainfall stations installed by Pacific HYCOS located on Guadalcanal. Elevation Period of Average No Station (m) Location and coordinates observations rainfall Henderson Airfield 5004652 Honiara 2 9º 25’ 44” E 160º 02’ 50” S ? - Open 1937 Honiara City 1934 5004051 DGMWR Office 71 9º 26’ 20” E 159º 56’ 20” S 2009 open 1986 only Honiara Hinterland 5004651 Mt Austin 250 9º 28’ 32” E 159º 58’ 49” S 2009 open NA Lower Tina 5006051 Rate School 52 9º 30’ 10” E 160º 06’ 46” S 2009 open NA Guadalcanal Plains 5006950 Tetere Prison 10 9º 27’ 06” E 160º 12’ 40” S 2009 open NA 333 Below Proposed powerhouse Temp No Tina 75 9º 31’ 52” E 160º 05’ 48” S 2009 open NA NA records too short for analysis Page 127 SOLOMON ISLANDS Limestone formations, Lungga Gorge 4. WATER RESOURCES areas of high impact activities such as logging and mining, or fish processing bounding the coastal 4.1 General Description fringe. These activities are considered to impact Due to the diversity and great geographic spread on the riverine and coastal environments due to of the Islands, water resources vary from one increased sediment loads especially during times island to the next where the smaller islands which of heavy rains.