A watershed is a physical feature on the landscape defined as the basin which collects rain water and directs it (by the slope of the land) to a stream (see Stream Ring). Every stream has its basin -- the land surfaces that drain towards it -- and the basin and the stream together comprise the watershed. The ahupua`a is a socio-economic unit with an ecological basis that largely derives from coincidence with the watershed. Ahupua`a boundaries tend to follow watershed boundaries because the resources within a watershed are interrelated -- connected to each other in ways that are stronger, more obvious, and more important than are resources from different watersheds. It is convenient to say that the watershed ends where the land and the stream meet the sea (i.e., at the shoreline). But the Hawaiian concept of ahupua`a does not end at the shoreline. It is recognized that the resources off the shore (see Marine Ring) have a relationship to the land and, of course, the people of that land.

The windward coast ....lies along the northeastern shores and inland valleys of the younger of the two volcanic masses which later joined to form the island of Oahu. This younger mass, known to geologists as the Ko`olau Volcano, gradually built its ridge in a northwesterly direction and began to fill in the ocean space which separated it from the dying Wai`anae Volcano to the westward. As the Ko`olau flows continued, the two mountain masses were joined and "what is now called the [central] Schofield Plateau resulted from the Koolau flows banking against the Waianae Mountain"(2). Thereafter active vulcanism ceased in the original firepits, and streams originating where the high peaks and cliffs caught the rain carved out great valleys on both the windward and leeward faces of the Ko`olau range. "Meanwhile the streams of the [older] Waianae Range had nearly dried up because the moist northeast trades were cut off by the growth of the Koolau Volcano"(2). Thus the fundamental characters of windward and leeward Oahu became fixed, from the point of view of the planter who was to dwell on the island millenia later.

The physical features of valley and shore line were to be greatly altered before the era of human habitation began. Great episodes of submergence and re-emergence of valley bottoms by and from the ocean occurred, during which new bays appeared across drowned valleys, valley heads became sea cliffs, and coral reefs became elevated sections of shore line. Later the upheaval of new cones and peaks and offshore islets further changed the topography.1

Windward O`ahu covers about 127 square miles. Only about one-fourth of this area is considered urbanized, which gives much of the region a rural or country atmosphere. Forest reserves and agriculture are the major land uses outside of the urbanized area.3

HIKING TRAILS   Numerous trails provide access to the more remote, mauka parts of Ko`olaupoko. There are also some trails closer to the urban center, for jogging, hiking, and biking. Descriptions of these, including in some cases, photographs and personal experiences, are provided on web pages maintained by hikers and hiking clubs on O`ahu. Try these for Ko`olaupoko scenes:

ENVIRONMENTAL EDUCATION (EE) Resources and Web Links Page

Na Ahupua`a o Ko`olaupoko (Watershed Ring)
  • Kualoa
  • Hakipu`u
  • Waikãne
  • Waiãhole
  • Ka`alaea
  • Waihe`e
  • Kahalu`u
  • He`eia
  • Kãne`ohe
  • Kailua
  • Waimãnalo
  • District Map