The Escarpment Subregion (SWIR)
Transition zone from plateau to lowlands.
Overview
The southern part of the [[SWIR Intermontane Basin (Astro)|Intermontane Basin]] of the [[South Western Inland Region (Astro Compendium)|South Western Inland Region]] transitions into the Escarpment subregion. Like the Intermontane Basin, the Escarpment is a subregion primarily defined by its elevation rather than by its biome or ecology. It is a corridor that runs northeast-southwest and is flanked by Range A in the west and Range B in the east. The Escarpment falls between latitudes 33.2 - 33.8°N and spans a hot to warm summer mediterranean climate (12°C - 19°C mean temperature) with particularities around the foothills of Ranges A and B.
The Escarpment is a small area of the entire SWIR. With an area of approximately 14,000 km², it makes up only about 2% of the entire Region, but is home to some of its most dramatic landscapes. The Escarpment begins at the plateau elevation of 1,000 - 1,200m in the north. Heading south, the terrain gradually slopes towards sea level with a steep mean gradient of approximately 0.76°. At around 55km south from the northern extent of the Escarpment, the Dau River cuts into the plateau’s edge forming deep rocky gorges.
The lower section of the Escarpment runs around 35km to the sea. The slope gradient eases towards the Southern Coast. The Dau River slows as the Dau Delta and it’s characteristics begin to show in the landscape with built up levees and flood plains.
| Attribute | Value |
|---|---|
| Latitude | 33.2 - 33.8°N |
| Köppen Climate Classification | Hot summer mediterranean climate, Warm summer mediterranean climate |
| Ecoregion | Mediterranean shrubland and woodland, riparian zone along the Dau River |
| Precipitation | 750mm - 1,500mm |
| Annual mean temperature range | 12°C - 19°C |
| Elevation range | 0–2,300m |
| Area | ~14,000 km² |
The Upper Gorge Area
The upper section of the Escarpment is characterise by the steep loss of elevation and the landscape etched by the Dau as it flows rigorously towards the Southern Coast. The mean inclination of 0.76° produces bedrock channels, rapids and the occasional waterfall.
The annual precipitation is between 750–900mm, making the gorge area a relatively wet area of the SWI Region. The valley-side of Ranges A and B facing the Southern Coast receive higher rainfall due to orographic lifting, with some areas seeing up to 1,500mm annual precipitation. The coldest months rarely fall below zero (coldest month mean 2–6°C) ensuring that the Dau River is flowing continuously throughout the year. The mean of the warmest month at 22–26°C.
The Dau River flood season occurs twice in the Gorge area. The first is between Months 13, 1, 2, and 3 with the mediterranean winter rainfall. The run off from the surrounding Ranges A and B contribute to significant run offs. The second flood season occurs late Month 5 and early Month 6. These early spring months show significant flooding caused by the snow melt from the northern reaches of the Dau and its headwaters. These floods bring fertile alluvial soils to the areas around the Dau River. Combined with the steep incline, both flooding seasons leave indelible marks across the landscape. Flash flooding is common. Discharge rates rise to between 35,000–42,000 m³/s, showing clear flood marks along the gorge walls. This makes the Upper Gorge area risky to travel during the spring and winter months.
| Attribute | Value |
|---|---|
| Latitude | ~ 32° - 33.2°N |
| Köppen Climate Classification | Warm summer mediterranean climate |
| Ecoregion | Mediterranean shrubland and woodland, riparian zone along the Dau River |
| Precipitation | 750–900mm |
| Annual mean temperature range | 12–15°C |
| Winter mean range | 2–6°C |
| Summer mean range | 22–26°C |
| Elevation range | 600m – 2,300m (mountain range inclusive) |
| The vegetation of the Upper Gorge area is Mediterranean shrubland and woodland, with density differences between the windward and leeward side of mountains. The sides receiving water from the South Coast sees denser and taller woodland trees. The leeward sides are rockier with sparse vegetation especially on the steepest sections of the mountains. The gorge itself is exposed rock faces with little vegetation. |
Seasonal Experience
The winter and spring months are the seasons of water. The rainfall of the winter and the spring flood pulses of the Dau make the upper gorge area loud and dynamic with the constant flow of water along the mountains, gorge face, and the Dau River itself. Movement is risky along the river and movement is mostly terminated during this time of the year.
In contrast, the summer sees the Dau River flow reduce significantly. The flow lessens to the extend that the gorge floor may become visible in parts. Rainfall ceases almost entirely, and navigation along the Dau River becomes possible both ways. The valley floor sees significant daylight, however parts of the gorge may be shaded significantly.
Autumn is the season of transition between the meandering summer and dramatic winter. Rains begin falling around Month 10, with river navigation becoming significantly harder from M11 onwards.
Flatlands Area
The gorge area gradually broadens out into a valley where the floodplains become wider. This transition occurs over a distance of approximately 35km. The mean climate at the beginning of this transition (elevation approximately 600m) is around 15-17°C, while at near-sea level it is a balmy 17-19°C. The climate is a hot mediterraneans one with the warmest months’ mean temperature reach a high of 27°C.
The flow of the Dau River slows, and corresponding proto-delta landscapes emerge as it approaches is terminus at the Southern Coast. The deposition of fine sediments and levees become visible. The vegetation likewise becomes those of floodplains, with meadows and reedbeds appearing the further south one travels.
| Attribute | Value |
|---|---|
| Latitude | ~ 32° - 33.2°N |
| Köppen Climate Classification | Hot summer mediterranean climate |
| Ecoregion | Mediterranean shrubland and woodland, riparian zone along the Dau River |
| Precipitation | 750–900mm |
| Annual mean temperature range | 17–19°C |
| Winter mean range | 9–12°C |
| Summer mean range | 24–27°C |
| Elevation range | sea level - 600m |
Seasonal Experience
The maritime effect of the South Coast is felt particularly directly in the flatlands. The four seasons are well defined and form the basis of human life. Winter is wet with water levels rising along the Dau and its distributaries. Flood plains become innundated, however navigation along the rivers and distributaries are still possible, as well as movement on certain tracts of land. The high levels of precipitation make winter a lush month, with mild temperatures ensuring a relatively comfortable existence.
The snowmelt pulse arrives on the Dau in spring in early Month 6. The valley floor becomes inundated, and the soils are replenished with the sediment carried along the Dau. Navigation along the river becomes easier once the flood season has passed.
Summer is the season of drought with very little rainfall. The River Dau is at a low flow, and navigation around the lower valley is at its highest. As the flow of the river recedes, the tidal influence of the coast is freer to push up the tributaries, with the upper [[Dau Delta]] becoming more tagible at the southern reaches of the valley. The warmest months see temperatures reaching an average of 24–27°C, resulting in maximum temperatures up to 35°C.
Autumn sees the return of rain. The landscape transforms again into lush greenery as the drought recedes. Rainfall becomes heavier as the months approach the winter solstice, with the Dau River swelling again, resulting in increasing difficulty of navigation.