Assignement-1 Bhavana.P 1130677 Topic: Catchment Assignment Characteristics Of Catchment Area and Key difference between Upper and Lower catchment: The key of the Selwyn river catchment area are mainly the structure where 60,000 hectares are covered from the ground water which is over all allocated. Near Darfield several tributaries are dry like Hawkins river, Black stream and Waianiwaniwa rivers. The flow rate of Hawkins river would be 1-10cumec/sec and that of Waianiwaniwa river is about 100cumec/sec. The electrical conductivity of water that is measured is about 104µs/cm. There is no algal mats present on the surface water. At Stop 2 of the field trip near Glentunnel Bridge pine forestry is present and there is warning of toxic algae present in the upper Selwyn river. The Hororata river which is a tributary if Selwyn river is dry, but the flow of this river helps in the increase of stream flow of the Selwyn river. There is low conductivity and presence of nitrates is also very less. About40 lowland streams flow into Selwyn which flows during July to October. The flow rate is about 20 meter/year. Th Boggy creek is abundant in water and has good draining and irrigation purposes. Nitrate concentration is about 3-4mg/litre. Selwyn river at Coes ford is popular for recreational activities. The emotional band is very high and the nitrate levels are very high. Cumulative impact of drought during the last few years has affected the river flow where it has resulted in algal growth and slime in the bottom of the river. Lll river is a spring fed river with sandy substrate and is well suited to macrophyte growth. The water is slow compared other parts of the river. Conductivity of the water at the time of trip is about 213.8µs/cm. There is lot of drainage from the farm land. Te-Waihora at Selwyn Huts is a lake called Ellesmere which is New Zealand’s 4-5th largest lake which is conditional when the amount of water is high then it is number 4 and when it is low then it is number 5. The sediment is very soft and is dangerous since the sand is silt condition. Nutrient and sediment contents are very high along. The conductivity in this region is about 19510µs/cm. Soils are low in phosphorous and pH. Differences between upper and lower catchment is that the soil moisture in the upper catchment is very low to moderate while in the lower catchment it is moderate to high. Soil drainage is high in the upper catchment compared to the lower catchment. Water table is also high in the upper catchment rather than catchment. Nutrient levels are high in the lower catchment compared to upper catchment. Main Uses of Surface and Ground water resources: The main uses of ground water in the upper catchment is for drinking, irrigation and dairy farming. The ground water is used for recharging of the aquifer and there is dryness in the lower catchment. Ground water seepage is about one third of Selwyn river near State Highway. Canterbury fish life is also mainly dependent on the amount of ground water present during dry season. Surface water is mainly used for restoring of the water for habitats of plants and animals, drinking purpose. There is more use of surface water during for recreational purpose near the Coes ford. In the near future, there is more usage of ground water for the agricultural purposes since there is need of food due to growing population. Ecosystem balance between land and water will be in more difficult to manage. Impacts of Land And Water Use: There is a shortage of ground and surface water, imbalance between water tables, decrease in the level of ground water. Due to deforestation, global temperatures are increasing which in return results in the increase of pollution due to CO2, methane and other carbon gases. There is an effect of drought from past several years which may increase to difficult situations for the production of food. Recreational activities like kayaking, swimming are effected due to the pollution of lakes and rivers. Proposed Goals: There should be immediate actions for the drought conditions, the government and local public should work collectively to bring some environmental policies into actions which would further help in the development of economic growth. To restore rivers, funds should be released from the government for the cleaning of the polluted lakes and rivers in the catchment of Canterbury and the rest of New Zealand. For recreational activities improvement people from different communities can come together and should give seminars and public speeches which in return helps in the development of tourism and increase in the GDP of the country.