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Determine the extent of human-related damage done to the Umlazi coastal wetland, by

identifying and contrasting former and current characteristics/conditions of the Umlazi coastal

wetland.

Natural factors and anthropogenic ones are found to be responsible for the change of ecosystem

(Zhao and Lai, 2007). The direct causes affect ecosystem, including climate change, the diversion of

freshwater flows, nitrogen loading, over-harvesting, siltation, changes in temperature of water, and

specie invasions. The indirect ones affect ecosystem via having influencing over one or several direct

factors. The indirect ones include population growth, economic development, social politics,

technological advancement, social culture, and life style and religion and so on (Zhao and Lai, 2007).

Human activities are becoming the main factors of wetland change at present. However, human

activities can accelerate or avoid wetland degradation, depending on how they change the

relationship between humankind and nature. The research on how the anthropogenic factors

influence wetland utilization structure can be greatly helpful for optimizing the structure of land use

and raising the utilization rate of wetland. Also the degradation and loss of wetland have been

caused by infrastructural construction, land use conversion, water withdrawals, pollution, over-

exploitation ofwood, and the introduction of invasive alien species (Zhao and Lai,2007; Katsuki et al.,

2009).Population growth and economic development are the two main forces causing wetland

degradation.

Development activities that involved excavation (or dredging) filling, clearing, draining, water

withdrawals and water diversion are believed to be the most significant and permanent impacts on

former Umlazi wetlands, these impacts vary from project to project, depending on the scale and

timing of the project.

Dredging and excavation in wetlands involved direct removal of wetland vegetation and underlying

wetland soil. This will reduce the elevation of the dredge area, allowing the area to be flooded with

deep water all the time, thereby eliminating the possibility of recolonization by wetland plant. For

example dredging or excavations are responsible for wetland losses associated with agricultural

conversion in Nabraska, canal construction in coastal Louisiana, Mississippi and Texas. (Citation). In

addition to the direct effect of removing wetlands vegetation and soil, dredging may impact

wetlands even if it takes place offsite. The dredging of Umlazi canal primarily for the reclamation of

the land for the economic development of the Umlazi area has contributed significantly to the direct

and indirect wetland losses in coastal area of Durban. Recent studies in the Mississippi delta have

showed a positive correlation between present of canal in the wetland area and the extent of

wetland loss (citation)

Filling the immediate and permanent effect of filling is to burry wetland vegetation, increasing the

elevation of the area for construction activities. Several types of solid waste are used as fill material.

Construction and demolition debris is used occasionally as stone, sand and gravel. The disposal of

type of solid waste in wetland carries the risk of detrimental chemical effects owing leaching of

nutrient and toxic chemical from the fill material. For example, filling is a major factor associated

with wetland loss for land levelling and agricultural conversion in Nabraska and Califonia (citation).

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Filling is often associated closely with dredging and excavation activities. The construction of Umlazi

canal involve dredging and excavation of material, the use of these dredge material as a fill to bury

wetlands vegetation may have led to the loss of the former Umlazi wetland. This practice not only

results in complete loss of the wetland but also create canal that are poor habitat for both flora and

fauna.

Water withdrawals and diversion alterations in the hydrological regime from large withdrawals of

water for municipal industrial use or large scale diversion of water for construction/ development

of site can cause various impacts on wetland ecosystem. The effects of the withdrawals and

diversion on downstream wetland are twofold, first upstream depletion may lower the water table

downstream freshwater wetlands, causing a temporary or permanent loss of wetland vegetation

and decrease in habitat value. Secondly decreasing fresh water inflow in coastal area will allow tidal

incursion of saltwater into the brackish and fresh water marshes. The increase in salinity to these

marshes will reduce species diversity and abundance as well as overall ecosystem productivity.

Water diversion and withdrawals also reduce the input of detritus into the estuarine flood chain.