- 4DHeritage team
The vital need to conserve both the built heritage and natural environment
Updated: Dec 3, 2020
Heritage sites such as the Siwa oasis depend on the local community as their guardian, preserving them for future generations. Traditional knowledge shared across the generations often has insights as to how delicate ecosystems can be sustained, and livelihoods supported. The Siwa oasis with its mud architecture, pools, palm groves, salt lakes and deserts illustrates the delicate balances that must be preserved as communities seek to preserve the past and map out a sustainable ways forwards into an increasingly uncertain future.
It is the local community that represent the generations that have tended the palm groves, sustained the built heritage on which tourism depends, and managed the water resources across the centuries.
However if the environment becomes degraded; the prospects for the community as a whole will be undermined. The future of built and the natural heritage are inextricably linked. The restoration of fortress of Shali is for nothing, if the natural resources of the oasis are not preserved as well. We have known for years that the agricultural land of the Siwa oasis is becoming depleted. In 2010, Prof Abo Ragab Samy of the Desert Research Centre, Cairo, highlighted the challenges 'it suffers many environmental problems: water logging, soil salinization, the inefficiency of disposed drainage water systems; deterioration in land productivity).
The scale of problem sometimes make the threat to the future seem insurmountable. Geographers and remote sensing experts have documented the inexorable demise of this once pristine oasis, but so far there has been no systematic and effective response to the ‘poisoning’ of the land, and the encroachment of new housing or industrial developments. But there is hope, and that comes from three directions.
On the 30 September 2020, President Abdel Fattah El Sisi gave a speech at the United Nations Summit on Biodiversity, during which he warned against the risk of the “steady decline in biodiversity and the rapid loss of natural resources”.
A month later, President Abdel Fattah El Sisi followed up specifically on the status of Siwa Oasis development projects, and agricultural wastewater treatment plants to provide access to irrigation water. The President directed his ministers and officials 'to ensure that the development of Siwa Oasis is carried out within a comprehensive and radical framework that preserves its distinctive heritage character and develops the unique tourist destination’s lakes, wells and natural water springs'.
At the ground level, thanks to the EU supported Shali restoration programme, a much greater focus on community empowerment and a holistic view of development. This is something we have explored in earlier webinars and blogs https://www.4dheritage.com/post/the-conservation-of-the-ateeq-mosque-a-case-study-in-holistic-heritage-stewardship. A vibrant and sustainable community is dependent on economic security, social welfare AND a healthy environment.
The third reason for optimism, and this webinar is about – is the revolution in temporal, spatial and spectral resolution for mapping, modelling and monitoring structures and landscapes. We can monitor changes not once in a decade, but season by season or week by week or day by day.
Instead of satellite monitoring providing images with a resolution of a hundred metres, a resolution of centimetres is possible. This means that data of soil degradation can be linked to individual landholdings.
The third reason for optimism, and this webinar is about – i revolution in temporal, spatial and spectral resolution for mapping, modelling and monitoring structures and landscapes. We can monitor changes not once in a decade, but season by season or week by week or day by day. Individual gullies being caused by surface water run-off in the archaeological site of Djenno-Jeno in Mali (see below).
The integrity of individual roof tops or health of agricultural plots can be monitored as shown in this image of the island city of Djenne in Mali.
Finally it is possible to monitor different spectra picking up insights into the level of stress affecting different vegetation or the soil moisture type.
A whole range of new sensors is opening up a whole new world before our eyes. Previously we were limited to seeing what was before our eyes – the visible spectrum.
Analysing the colour of vegetation using different wavelengths can reveal how fertile the ground is and the stress on vegetation. The most common approach uses the Normalized Difference Vegetation Index (NDVI).
NDVI was originally developed and applied to analyse satellite images but with greater access to terrestrial and aerial multispectral sensors, the indicator can now be used much more easily at selected sites and at higher resolutions. NDVI works by comparing the ratio of red and near-infrared light reflected from a surface. Plants absorb solar radiation in the photosynthetically active radiation (PAR) spectral region, but outputs of different wavelengths of light depend on the condition of the vegetation.
For instance, plants undergoing some form of stress may not be photosynthesising optimally, resulting in greater refection of red light (hence the normal browning of vegetation during dieback or stress). This greater proportion of reflected red light would then skew the resultant NDVI result, potentially highlighting a problem with a field of crops for example.
The deep red areas in this image of the Djenne Jeno archaeological site show where the soil is very thin or degraded.
Soil probes can then be used for ‘ground truthing’ the data and provide an even better diagnosis of the drivers of any degradation or contamination.
The real value comes from integrating all these monitoring techniques to improve natural resource management of fragile ecosystems - a multi parametric approach.
This complex data can then be shared with the stakeholders in the community in a way that makes it simple and intuitive to understand. It can be provided in real time with much greater transparency than ever before, helping to ensure that the different stakeholders in the community have access to the same datasets and a seeking to solve the challenges they face in a way that is sustainable for the community, and provides greater security for every household, individual and generation.