General Info

The Umm Al Gramme wetland serves as the main outlet for both the Wadi Al-Hanawi basin, which spans approximately 19,039 hectares, and the Wadi Al-Masheib basin, covering around 6,434.71 hectares. Additionally, it receives surface runoff from a collection of smaller basins (Al-Wushka, Bu Sulufa, and Al-Naghar) with a combined area of about 1,085.86 hectares. During the rainy seasons, surface runoff from these basins flows into the Umm Al Gramme wetland, making it a central water catchment area for multiple basins in the region.

Topography

The topography of the Umm Al Gramme wetland area ranges from -4 below sea level to elevations reaching more than 50 meters above it. The wetland is encircled by plateaus with gentle to moderate slopes, forming a natural boundary that directs water flow into the wetland. These plateaus, primarily composed of limestone and dolomite, exhibit signs of weathering and erosion, contributing to the rugged terrain surrounding the wetland. The topographical features guide water flow toward the wetland, creating a natural catchment area. Coastal sand deposits along the Mediterranean boundary act as a buffer, influencing the wetland's water levels and salinity. This interaction between the topography and coastal geography plays a crucial role in the hydrological dynamics of the Umm Al Gramme wetland.

Geology

1. Overview of the Geological Units

The surface geology of the Umm Al Gramme wetland areaprimarily consists of sedimentary deposits from the Tertiary and Quaternary periods. These sediments reflect both terrestrial and aquatic deposition processes, varying according to the environmental and geomorphological conditions of the wetland.

2. Tertiary Deposits

The Tertiary deposits are represented by the Al-Faidiyah Formation, which dates from the Upper Oligocene to the Lower Miocene periods. The Al-Faidiyah Formation consists of two main members:

  • Limestone Member: This member represents the dominant lithological unit, which is well exposed and consists of carbonate-rich materials.
  • Claystone Member: Found in some parts of the region, this unit contains fine-grained clay sediments, likely formed in a more low-energy environment compared to the limestone.
Upper Oligocene-Lower Miocene 1 Upper Oligocene-Lower Miocene 2 Upper Oligocene-Lower Miocene 3 Upper Oligocene-Lower Miocene 4 Upper Oligocene-Lower Miocene 1 Upper Oligocene-Lower Miocene 2 Upper Oligocene-Lower Miocene 3 Upper Oligocene-Lower Miocene 4

3. Quaternary Deposits

The Quaternary deposits within the wetland are more diverse and are divided into:

  • Terrestrial Deposits: These are land-based sediments that likely originated from erosion and other geological processes in the surrounding region.
  • Aquatic Deposits: These sediments were formed in water, influenced by the hydrological dynamics of the wetland. The composition of these deposits varies significantly depending on the depositional environment, ranging from fine silts and clays to coarser materials. Organic matter is also present in some areas, suggesting the accumulation of biological material over time.
Quaternary Deposits 1 Quaternary Deposits 2 Quaternary Deposits 3 Quaternary Deposits 4 Quaternary Deposits 1 Quaternary Deposits 2 Quaternary Deposits 3 Quaternary Deposits 4

Geomorphology

Overview of the Geomorphological Units

The Umm Al Gramme Wetland is divided into distinct geomorphological units, as represented in the legend. These units reflect the interactions between surface water, groundwater, and sediment deposition processes. Seasonal and natural processes contribute to a dynamic landscape, supporting diverse ecological habitats.

1. Island

The Island within Umm Al Gramme Wetland is composed of resilient limestone and supports minimal vegetation due to harsh environmental conditions, including exposure to wind and salt.

  • Elevation: Approximately 3 meters above sea level.
  • Geology: Composed of solid limestone from the Al-Faidiyah Formation.
  • Vegetation: Sparse vegetation, primarily salt-tolerant shrubs.
Island 1 Island 2 Island 3 Island 4

2. Main Wadi Outlet

The main wadis, including Wadi Al-Hanawi and Wadi Al-Mutayfiyal, discharge seasonal runoff into the wetland, providing nutrients and creating temporary ponds.

  • Elevation: Ranges from 3 to 12 meters above sea level.
  • Sediment Composition: Dominated by red clays transitioning to silts near the wetland.
  • Ecological Function: Essential for maintaining water balance and supporting biodiversity.
Main Wadi Outlet 1 Main Wadi Outlet 2 Main Wadi Outlet 3 Main Wadi Outlet 4

3. Sand Beach

Extending along the eastern edge, the sand beach acts as a natural barrier between the lake and the Mediterranean Sea.

  • Sediment Composition: Fine white sands with shell fragments, gypsum, and carbonate minerals.
  • Ecological Role: Supports coastal vegetation and serves as a buffer against tidal intrusion.
Sand Beach 1 Sand Beach 2 Sand Beach 3 Sand Beach 4

4. Tidal Plain

The Tidal Plain experiences periodic flooding due to tidal movements, creating habitats with mixed salinity.

  • Sediment Composition: Fine silts and clays with organic enrichment from tidal inflows.
  • Ecological Role: Supports salt-tolerant vegetation and migratory birds.
Tidal Plain 1 Tidal Plain 2 Tidal Plain 3 Tidal Plain 4

5. Brackish Water Ponds

Brackish Water Ponds, formed by groundwater seepage, are scattered in low-lying areas near the wetland’s edges.

  • Hydrology: Semi-saline, with salinity varying by location.
  • Sediment Composition: Thin silty clay layers with moderate salinity.
Brackish Water Ponds 1 Brackish Water Ponds 2 Brackish Water Ponds 3 Brackish Water Ponds 4

6. Wadi Channel

The Wadi Channel channels seasonal floodwaters and sediment into the wetland, creating nutrient-rich deposits.

  • Sediment Composition: Mix of light brown soils, gravel, and occasional boulders.
Wadi Channel 1 Wadi Channel 2 Wadi Channel 3 Wadi Channel 4

7. Saline Water Ponds

Saline Water Ponds have high salt concentrations due to periodic tidal influence and groundwater seepage.

  • Sediment Composition: Saline silts and clays.
  • Ecological Role: Habitat for salt-tolerant species.
Saline Water Ponds 1 Saline Water Ponds 2 Saline Water Ponds 3 Saline Water Ponds 4

8. Wetland Bank (Shrub Swamps)

Surrounding the lake, these banks are characterized by dense shrub vegetation supported by groundwater seepage.

  • Elevation: Ranges from -1 to +4 meters above sea level.
  • Sediments: Composed of silt and clay, rich in organic matter.
Wetland Bank 1 Wetland Bank 2 Wetland Bank 3 Wetland Bank 4

9. Burdi Swamps

Burdi Swamps are scattered across the wetland and are formed by groundwater seepage, providing semi-saline conditions.

  • Hydrology: Supported by groundwater seepage, with semi-saline conditions.
  • Sediment Composition: Thin silty clays with variable salinity.
Burdi Swamps 2 Burdi Swamps 2 Burdi Swamps 3 Burdi Swamps 4

10. Flood Banks

Flood Banks are created by elevated sediment deposits, forming a buffer between the lake and the surrounding areas.

  • Sediment Composition: Silt and clay deposits enriched with organic material from plant decay.
Flood Banks 1 Flood Banks 2 Flood Banks 3 Flood Banks 4

11. Umm Al Gramme Lake

Covering approximately 53 hectares, Umm Al Gramme Lake is the focal hydrological feature, fed by both surface runoff and groundwater inflows.

  • Depth: Ranges from -6 to +5 meters with seasonal fluctuations.
  • Sediment Composition: Fine sands, silts, and clays with organic material from decomposed vegetation.
Umm Al Gramme Lake 1 Umm Al Gramme Lake 2 Umm Al Gramme Lake 3 Umm Al Gramme Lake 4 Umm Al Gramme Lake 1 Umm Al Gramme Lake 2 Umm Al Gramme Lake 3 Umm Al Gramme Lake 4

12. Rocky Hills

The Rocky Hills surround the wetland, forming its northern and southern boundaries. These plateaus consist of highly resistant rock formations from the Al-Faidiyah Formation (Oligocene-Miocene), mainly composed of limestone and dolomite. This geomorphological unit is key in preventing erosion and shaping the overall topography of the wetland.

  • Elevation: The hills range in height from 3 to 18 meters above sea level, with the highest elevations found in the west, southwest, and northwest.
  • Karst Features: The limestone shows evidence of extensive weathering and erosion, including numerous fractures, cracks, and karstic voids.
  • Soil Cover: The plateaus have a thin soil layer (less than 50 cm) consisting of light brown calcareous soils with rock fragments, pebbles, and gravel.
Rocky Hills 1 Rocky Hills 2 Rocky Hills 3 Rocky Hills 4

13.Rock Hills Plain

The Rock Hills Plain forms the elevated plateaus within the Rocky Hills, characterized by its reddish-brown, light soil and gently undulating terrain. This plain, situated within the Al-Faidiyah Formation (Oligocene-Miocene), is primarily composed of limestone and dolomite, which offer a stable structure and natural erosion resistance. Despite the semiarid climate, rainfed agriculture is practiced here, taking advantage of the seasonal rainfall and the soil's capacity to retain moisture for limited periods.

  • Elevation: The plateaus range from 3 to 18 meters above sea level, creating a level but slightly varied topography.
  • Soil Composition: The soil is a thin layer of reddish-brown sandy loam mixed with rock fragments, ideal for rainfed crops adapted to the semiarid conditions.
  • Karst Features: Extensive fractures, cracks, and karstic voids due to weathering enhance the plain’s capacity for groundwater recharge and seasonal water retention, benefiting agricultural practices in this dry environment.
  • Vegetation: Limited vegetation, consisting of drought-resistant shrubs and crops suited to rainfed farming.
Rock Hills Plain 1 Rock Hills Plain 2 Rock Hills Plain 3 Rock Hills Plain 4

Water Salinity

Salinity Distribution Overview

The Umm Al Gramme Wetland exhibits a complex salinity gradient, influenced by both marine influx and freshwater sources. The salinity distribution across the wetland is mapped with distinct zones, ranging from highly saline to lower-salinity areas. Key findings on water salinity include:

  1. High Salinity Core (>22 g/l):
    • Concentrated in the central and northern parts of the wetland, exceeding 22 grams per liter. These areas show strong influence from seawater infiltration, limited freshwater dilution, or evaporation-driven salt concentration.
    • This highly saline core may support specialized flora and fauna adapted to extreme salinity conditions.
    2. Saline Water Ponds 2
  2. Transitional Zones (20-22 g/l, 18-20 g/l):
    • Located around the high salinity core, with salinity levels between 18 and 22 grams per liter. These zones likely experience minimal freshwater input, creating a gradient suitable for some salt-tolerant plant species and less salt-adapted organisms.
  3. Moderate Salinity Areas (16-18 g/l, 14-16 g/l):
    • These areas are found further from the core, with a gradual decrease in salinity. Occasional freshwater runoff or seepage might dilute the salt concentration, supporting a wider variety of species.
  4. Lower Salinity Margins (12-14 g/l, 10-11 g/l, 9-10 g/l):
    • Located at the periphery of the wetland, with salinity levels between 9 and 14 grams per liter. These areas are influenced by freshwater inflows or sources like minor wadis or groundwater seepages, which help reduce salinity levels.
    • The lower salinity supports a diverse ecosystem that includes both salt-tolerant and freshwater species.
  5. Freshwater-Influenced Zones (<=9 g/l):
    • These areas have salinity levels below or around 9 grams per liter, primarily located near the edges of the wetland where seasonal wadis or groundwater springs contribute freshwater. These zones foster unique habitats for freshwater-dependent species, enhancing the wetland's biodiversity.

Geomorphological Unit Influence on Salinity:

  • Umm Hufayn Lake: The central feature of the wetland, the lake is positioned near moderate to high salinity zones. Given its proximity to the main wadi outlet and wetland bank, it likely experiences a mix of freshwater inflows from the wadi and saline water from adjacent swamps and ponds. Continuous monitoring of water quality here is crucial.
  • Main Wadi Outlet and Wadi Watershed: These units play a significant role in transporting seasonal runoff and freshwater into the wetland, which can temporarily dilute salinity levels in areas closer to the small wadi watershed. However, proximity to saline water ponds may contribute to periodic spikes in salinity.
  • Sand Beach and Sea Barrier: These geomorphological features along the coastline act as natural buffers, but also contribute to saline intrusion into the wetland.
  • Swamps and Ponds: The presence of brackish and saline water ponds in and around the wetland bank indicates zones of stagnant water with high evaporation rates, further concentrating salts. These areas are highly vulnerable to salinity spikes during dry seasons.

Note: The salinity shown is an average of annual measurements. It varies throughout the year due to the connection with seawater and the input of surface water from seasonal wadis.

Water Depth

Water Depth Distribution Overview

Water depth in the Umm Al Gramme Lake wetland ranges from 0 to over 3.5 meters, with the deepest areas observed in the northern-central zones of the wetland. Key patterns include:

  1. Deep Water Zones (>3.5 meters):
    • Primarily concentrated in the northern-central areas of the wetland, indicated by darker blue shades.
    • These zones are located near the Umm Al Gramme Lake and reflect areas of significant water accumulation.
  2. Moderate Water Depth Zones (2-3.5 meters):
    • Found throughout the central and some northern sections, where water depth is substantial but not as deep as the core regions.
    • These zones are likely influenced by the proximity to main wadi outlets and water inlets that contribute to seasonal runoff.
  3. Shallow Water Zones (0.5-2 meters):
    • Spanning across various peripheral portions of the wetland, particularly near the coastal sand beaches and swamps.
    • These areas experience shallower water due to geomorphological features that restrict water accumulation.
  4. Very Shallow and Undefined Zones (<0.5 meters):
    • Concentrated near the inland areas, represented by lighter blue or undefined regions.
    • These areas may experience periodic or temporary water coverage during rainy seasons or wadi flow, with limited water retention capacity.
Water Depth Map

Geomorphological Unit Influence on Water Depth:

The geomorphological features of the Umm Hufayn wetland play a significant role in influencing water depth distribution. Key relationships include:

  • Umm Al Gramme Lake (Deepest Zone): This is the primary water body of the wetland, where the water depth exceeds 3.5 meters in the northern-central region. The lake acts as the focal point for water accumulation and seasonal runoff inflows.
  • Main Wadi Outlet and Watershed (Moderate Zones): These areas help transport water into the wetland, particularly influencing moderate-depth zones (2 to 3.5 meters), where runoff contributes to temporary water buildup.
  • Coastal Sand Beach and Swamps (Shallow Zones): These regions along the eastern part of the wetland contain shallower water zones, likely due to sediment deposition and the influence of wind-driven processes that prevent deep water accumulation.
  • Rocky Hills and Plains (Undefined Zones): The rocky hills surrounding the wetland, with elevations higher than 0.5 meters, form the perimeter of the wetland, limiting water retention and contributing to the very shallow water zones.

Note: The water depth shown is an average of annual measurements. It varies throughout the year due to the connection with seawater and the input of surface water from seasonal wadis.